Steve http://members.rogers.com/steve.brady "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
motion detection, ussually radio waves in the K or X band because they would always set off radar detectors. I don't know if thats what they still use but 10 years ago it was. Heat detection doesn't work because the door could be facing east or west and be blinded by the sun.
Post Edited (Paul Baker) : 2/14/2005 5:29:09 AM GMT
Steve http://members.rogers.com/steve.brady "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
I learned an interesting lesson in automated systems and safety interlocks as a child. When I was about 5 or 6 our local grocer open a brand new modern Supermarket. It even had these really cool doors that would open automatically when you stepped on the pad in front of them. These were the old style single swinging doors, one for in and one for out.
I was playing around with the doors and wondering why the 'out' door didn't open when I stepped on the pad outside the door. After all, the 'in' door had an identical pad on it and it opened. While standing there puzzling this, a customer walked up to the 'out' door from inside and the door opened... bonk into my nose and pushing me off my feet. There was no safety interlock to prevent the door from opening if somebody was standing on the pad outside the door.
That I don't know, sorry. But Im inclined to say neither, screw drive is too slow for the rate they operate, actuators (at least the ones Im familiar with) don't have enough throw to open an entire door. This is a stab in the dark, but to open them it may be a counter balance with a screw drive to close them (they close slower than they open, they also make more noise when closing, older ones seem to groan when they close but make a nice whoosh when opening). Next time I'm at one I'll examine it to see what kind of clearence they have for various mechanisms. (the one I ussually goto is a swing type, Ill make a point to goto the one down the street next time)
Haha....there's going to be some goofy people (myself included) staring at doors as they're opening/closing.· They'll think we're out on a day pass! haha
I've worked with mag-lock power doors, but certainly don't recall how they were built (big AC motor and a cam/lever?!).
But certainly there's not a whole lot to those sliding doors.· So whatever they put in to open/close, it's built within the first few inches of the surrounding frame.
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Steve http://members.rogers.com/steve.brady "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Thats why Im inclined to believe there is a weight in that frame with a pulley and cable, much like the old wooden sash windows. The opening mechanism is so smooth there arn't many mechanical options which would work that fast and clean (that isn't going to outrageously expensive). Additionally those doors have a safety mechanism which permit you to swing them open in the even of a power loss which further limits what could be used.
Try this circuit.· The relays are automotive ISO 1 inch cubes.· They are rated at 40 amps.· The benefit of this circuit is that when the door reaches the end of travel the relay that had been pulled in will open and the motor will brake very quickly as it tries to force its generated current through the relay's NC terminals.· This circuit is essentially the same as that used to drive the Tilt/Trim systems on many outboard motors.· If you get a high quality Hella or P&B (Siemens) relay it will be good for about 50,000 cycles.
Edit: sorry the first image is so big, Ill try to attach a jpg.
AH....but what's the fun in buying off the shelf! hehe
Wonder what happens when your pooch likes to lie in the sun as it comes through the patio door window?!· It'd get cold in a hurry come winter!
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Steve http://members.rogers.com/steve.brady "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
The link that Paul provides is to a company selling the DoorMate product which is at www.doormate.com. Reading the FAQ they describe the opener as "a solid steel threaded screw drive". Sounds like a good way to do it. Watching their video, the door only takes a few second to open.
If you were to couple a threaded drive rod (Can't remember the technical term for them) to the output shaft of the motor and mount a guide with an inside thread on the door I think it would work. An industrial surplus house might be a good place to look for such a beast. Or if somebody can come up with the real name (other than whatzit) you should be able to find something online.
All, Thanks for the info about the doggie doors, but I exhausted all those possibilities 2 weeks ago. The slider is a go. All the mechanical stuff is in place. I have a sealed lead acid battery (12V/5AH) for power ... still looking for a trickle/float charger (500-750mA) for this.
Hulk,
I your circuit ...
I have no experience with this stuff, and need help spec'ing parts.
- Do I need the transistors to drive the relay?
- If so, what transistors, what size resistors?
- Are the diodes part of the relay? If not, what diodes?
- Are these two parts of a DPDT relay, or 2 separate relays? Couldn't I use an SPDT? Why not?
- If I power the opening and closing for a specified time, do I need the switches?
- Are the down-pointing triangles hooked up to common on the battery?
- What did you use to draw the circuit?
- Is line length important from the switches that initiate the opening or closing (not the ones in your circuit, but that trigger the stamp)? For these, could I use some cat II I have lying around?
1. Use a pulse charger like the "surecharge iv" from northern tool. A pulse charger will greatly lengthen the life of the battery as we are finding out in the solar community. I have 12 volt lead acid batteries over 10 years old still working fine using the surecharge iv.
2. Use 2 spdt relays for the motor control. Both open or both closed, nothing happens
either closed the motor will turn. The normally closed contacts are both power ground (-) and the normally open contacts are (+). This causes braking in many types of dc motors.
Without adding extra push buttons for testing, if the relays are not enclosed, all you have to do to test either movement is push down the armature on one of the relays, with a plasic ballpoint pen.
73
spence
k4kep
-Do I need the transistors to drive the relay?
The relays draw about 135 mA, too much for the BS2
- If so, what transistors, what size resistors?
470 ohm (estimated by I base >/= 2 X 135 mA/hfe so: (source voltage – base/emitter drop)/470) is approx = 2 x .135/35. ·Transistor: 2N2222 (really any garden variety NPN transistor that can take say 200 mA Ic)
- Are the diodes part of the relay? If not, what diodes?
1N4004·
- Are these two parts of a DPDT relay, or 2 separate relays? Couldn't I use an SPDT? Why not?
Its possible, but the relays shown will handle the current and they’re cheap
- If I power the opening and closing for a specified time, do I need the switches?
The switches will allow FULL open and closed without them it’s a crapshoot
- Are the down-pointing triangles hooked up to common on the battery?
Yes, battery ground.
- What did you use to draw the circuit?
It’s freeware expressPCB.com. I think it was recommended by Jon Williams on this forum
-I would locate the transistors close to the BS2 and run the necessary long lines from the Collector to the relay- if there's going to be any inductance in the long line I don't want the BS2 to experience it.· Also it's best to mount the freewheeling diode directly to the relay.· Since long lines are necessary, you may want to put an additional diode· from the collector to the emitter (cathode on collector) to protect it from line ringing.
Best of luck!
I've attached a circuit that JonW sometimes posts for those wanting to connect a relay to a stamp.
The circuit referenes connecting to Vdd as the source in the tree...so, based on that you might look for a 5V relay....
but if you are using a separate supply for the motors (12V) then maybe automotive relays will be fine.· It's the transistor that will switch the 12V side for you.· This would totally separate your supplies, which is nice....the 2N2222 is a nice transistor to use and a 1N4004 (I think..always confused with the 1N4001) should be fine across the coil.
because you're running a motor, I'd say DEFINATELY separate the supplies.· Of course, you MIGHT need the grounds to be common (odds are yes) in which case you may have some noise bleed back from the motor...it happens, but can be dealt with later.
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Steve http://members.rogers.com/steve.brady "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Hello Steve,
I am recommending the automotive 12V relays because they are very sturdy. The NC contacts in the circut shown above are the weak link. They take an awsome beating during dynamic braking. I'm not sure of any other relays that will stand up to it. I have lab test time on the above so I can propose it without fear.
The dynamic brake can be avoided with some circuit modification, but I think he'll like it to give some precision to the full open and full closed door position.
And the grounds MUST be connected together for this to work. The BS2's input into the transistor is referenced to the emitter ground -- which MUST be the same ground the 12 Volt DC is using.
Having said that, there should be no problem setting the 'Vdd' in the diagram to 12 volts, while the BS2 is driven by +5. Make sure the BS2 Vdd is NOT set to +12, though, that would destroy the BS2.
Thank you all for the suggestions. Because of them, I'm making good progress, though not as fast as I would have liked!
I'm using a Mercedes window lift motor powered by a 12V 5Ah SLA to operate the slider. I have it connected to the slider with cables and pulleys to open and close, and it works fine!
The battery is "continuously" float charged with a 750mA fully automatic battery tender.
I couldn't find SPDT 40A automotive relays in town, so I'm using 4 SPST 30A automotive relays instead.
Attached is the schematic I adapted from Hulk's recommendation. Before I finish wiring it up and frying by Stamp (or dog), I was hoping I could get some feedback and some questions answered ...
- Have I got it wired up so it will work?
- I've changed the 470ohm resistors to 220ohm because my Stamp comes mounted on the "HomeWork Board" and the manual shows that with this board all pins are already protected with 220ohm resistors (so I figured 220+220 was close to 470). Is this OK?
- In place of the momentatry SPST NC switches Hulk recommended, I'm using momentary SPDT roller microswitches for S1 and S2, with the NC configuration used to energize the relays as in Hulk's design. I'd like to use the NO pin as input to the Stamp, to detect full open and full close of the slider. Will this work? What goes in between the switches and the pins on the Stamp to accomplish this?
- With the HomeWork Board, I have 3 voltage sources available that I could use for V+ and V- in the circuit to energize the relays. Which should I use?
a) 12V from the SLA battery that is powering the motor
b) 9V Vin from the small 120VAC/9VDC adapter that is powering the HomeWork Board (it replaces the 9V battery on the board)
c) Vdd and Vss from the on-board LM29366
- Do I need to tie the 12V ground to Vss? Since these appear as separate circuits in the schematic, it seems that I don't need to if I don't use the 12V to energize the relays, as in a) above
It's drawn a little oddly from your "normal" H-Bridge diagram -- but basically yes, you seem to have it correct. Since the 12 volts only appears across the motors (isolated by the relay contacts) you don't need to connect the 12 volt grounds to the BS2 ground.
You know you'll need to be VERY careful what order you enable (turn-on) the relays, and what sets of relays you turn on at the same time, or you'll get a dead short across your 12 volt supply. You might want a 20 amp fuse in there, just in case.
Thanks. Yeah, it probably looks funny, 'cause I've never seen an H bridge, just tried to extrapolate from Hulk's schematic.
I figured I needed to be 110% sure on the order of firing the relays, but I took your advice and bought a fuse.
I could still us some answers before I connect any power to the controller. (I'm a little nervous about frying the Stamp.) I've attached my updated schematic.
I would feel better if someone could verify that the HomeWork board has the 220 ohm resistors on all pins (not shown on my schematic) and that I should reduce the resistors in the circuit to 220 instead of the original 470 ohms suggested by Hulk.
Also, I've added resistors R1 and R2 between the switches and V- so I can detect switch closure with the Stamp. Is this right? Is 10Kohms appropriate for these? I haven't added a resistor in the lines to the Stamp (again, because of the assumption that the pins are protected by resistors on the HomeWork board). Is this OK too?
I still need some help in selecting V+ and V-. I'm afraid that Vdd and Vss may not be enough to power the relays. Can anyone comment on this? Or, tell me how much the automotive relays draw? And, if they have a minimum voltage requirement?
What about the 9V powering the HomeWork board; would this work for the relays? I can get small 9V supplies at 300mA, 800mA, 1200mA, and 1500mA. Will this be safe to be used as the inputs to the Stamp on P5 and P6?
Or, should I use the 12V from the 5Ah SLA battery? Would this be safe for the Stamp?
I notice in that schematic that you use V+ and V-....are you sure that it isn't V+ and Gnd?!· V- would indicated a need for a dual supply; positive and negative voltages!
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Steve http://ca.geocities.com/steve.brady@rogers.com/index.html "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
V- probably should be Ground (aka VSS), and it MUST be connected to the BS2 ground.
If you want to use +12 (and if those really are automotive relays, then they probably need 12 volts), then P5 and P6 should have a 22 Kohm resistor in series to the pin. The BS2 has 'protection diodes' in the input pins (inside the PIC chip) which will 'clip' any signal over +5 to the BS2. These are normally used when recieving 'raw' RS-232 (+-12 volts) and work fine as long as the input current is limited by a 22 Kohm resistor. Keep the 10Kohm resistor in the 'Ground' leg -- that will pull the signal to zero when the +12 is not enabled.
And don't mind Steve_b's "-V" comment -- if you were an electrical engineer with lots of experience, or this was an op-amp design, this would imply a dual voltage. As you are building a prototype, and it's YOUR schematic after all, and you're not using an op-amp, -V can be ground.
I don't know what relays you are using. They may or may not need a resistor in the 'collector' leg of the transistors. If they really ARE Autmotive relays, they probably don't need a resistor. You might populate the circuit with JUST ONE relay, and measure the current through it and voltage across it when energized. This value is very important -- if it's too high, you may need TIP120 darlington transistors to deal with it.
The 220 ohm / 470 ohm resistors on the base legs of your transistors are to limit the base current. The way a transistor works is as a current device. Current going into the base enables lots of current to go into the collector -- and both currents exit through the emitter. The multiplicative factor is called Hfe, and varies based on what part you've selected.
For digital purposes, we want to 'saturate' the transistor, so it is firmly in the 'on' state. I don't know what transistor you are using, nor its Hfe. These are the critical pieces to know if the base current enables enough current to switch the transistor fully 'on'.
A rose by any other name ... ;-> I'm an editor (right now), so I'm sensitive to the importance of accurate use of jargon; I've relabeled V- to GND.
But, the bigger question for me is what it's actually connected to. I gather from the discussion that using the 12V battery to drive the relays is OK, so I've shown the positive terminal of the battery connected to the full-open/full-closed switches (S1 and S2).
As I understand it now, I want to tie all those GNDs to the ground (minus, common, black) terminal on the battery, AND to Vss on the HomeWork board. What about to the ground of the 9V power supply powering the HomeWork Board?
I've added the other resistors according to what I think I got out of your note. Please let me know if I got it backwards.
The relays were purchased at an auto parts store. They are labeled "Heavy Duty Relay", model DF005, either by Federal Mogul or Blazer Intl Corp, and are rated at 30A. I believe they are really "automotive" relays.
If anyone has any last minute warnings, now's the time! I hope to fire it up tomorrow evening.
P.S. As I noted in the schematic, the transistors are 2N2222. So, what is the size of the base resistors (and do I need to consider the 220 ohm resistors that are not shown but supposedly built onto the HomeWork board to protect each pin of the Stamp)?
Comments
And what kind of mechanism do grocery stores use?
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Steve
http://members.rogers.com/steve.brady
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Post Edited (Paul Baker) : 2/14/2005 5:29:09 AM GMT
screw drive? actuator?
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Steve
http://members.rogers.com/steve.brady
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
I was playing around with the doors and wondering why the 'out' door didn't open when I stepped on the pad outside the door. After all, the 'in' door had an identical pad on it and it opened. While standing there puzzling this, a customer walked up to the 'out' door from inside and the door opened... bonk into my nose and pushing me off my feet. There was no safety interlock to prevent the door from opening if somebody was standing on the pad outside the door.
Jim
I've worked with mag-lock power doors, but certainly don't recall how they were built (big AC motor and a cam/lever?!).
But certainly there's not a whole lot to those sliding doors.· So whatever they put in to open/close, it's built within the first few inches of the surrounding frame.
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Steve
http://members.rogers.com/steve.brady
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Edit: sorry the first image is so big, Ill try to attach a jpg.
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Basic stamp Newbie
Post Edited (Hulk) : 2/14/2005 5:55:41 PM GMT
Dave
plus this http://www.moorepet.com/moorepet/index.cfm?fuseaction=customer.product&product_code=171&category_code=
Wonder what happens when your pooch likes to lie in the sun as it comes through the patio door window?!· It'd get cold in a hurry come winter!
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Steve
http://members.rogers.com/steve.brady
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
If you were to couple a threaded drive rod (Can't remember the technical term for them) to the output shaft of the motor and mount a guide with an inside thread on the door I think it would work. An industrial surplus house might be a good place to look for such a beast. Or if somebody can come up with the real name (other than whatzit) you should be able to find something online.
Jim
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Basic stamp Newbie
Hulk,
I your circuit ...
I have no experience with this stuff, and need help spec'ing parts.
- Do I need the transistors to drive the relay?
- If so, what transistors, what size resistors?
- Are the diodes part of the relay? If not, what diodes?
- Are these two parts of a DPDT relay, or 2 separate relays? Couldn't I use an SPDT? Why not?
- If I power the opening and closing for a specified time, do I need the switches?
- Are the down-pointing triangles hooked up to common on the battery?
- What did you use to draw the circuit?
- Is line length important from the switches that initiate the opening or closing (not the ones in your circuit, but that trigger the stamp)? For these, could I use some cat II I have lying around?
Thanks, all, for all the help.
1. Use a pulse charger like the "surecharge iv" from northern tool. A pulse charger will greatly lengthen the life of the battery as we are finding out in the solar community. I have 12 volt lead acid batteries over 10 years old still working fine using the surecharge iv.
2. Use 2 spdt relays for the motor control. Both open or both closed, nothing happens
either closed the motor will turn. The normally closed contacts are both power ground (-) and the normally open contacts are (+). This causes braking in many types of dc motors.
Without adding extra push buttons for testing, if the relays are not enclosed, all you have to do to test either movement is push down the armature on one of the relays, with a plasic ballpoint pen.
73
spence
k4kep
73 spence
k4kep
The relays draw about 135 mA, too much for the BS2
- If so, what transistors, what size resistors?
470 ohm (estimated by I base >/= 2 X 135 mA/hfe so: (source voltage – base/emitter drop)/470) is approx = 2 x .135/35. ·Transistor: 2N2222 (really any garden variety NPN transistor that can take say 200 mA Ic)
- Are the diodes part of the relay? If not, what diodes?
1N4004·
- Are these two parts of a DPDT relay, or 2 separate relays? Couldn't I use an SPDT? Why not?
Its possible, but the relays shown will handle the current and they’re cheap
- If I power the opening and closing for a specified time, do I need the switches?
The switches will allow FULL open and closed without them it’s a crapshoot
- Are the down-pointing triangles hooked up to common on the battery?
Yes, battery ground.
- What did you use to draw the circuit?
It’s freeware expressPCB.com. I think it was recommended by Jon Williams on this forum
-I would locate the transistors close to the BS2 and run the necessary long lines from the Collector to the relay- if there's going to be any inductance in the long line I don't want the BS2 to experience it.· Also it's best to mount the freewheeling diode directly to the relay.· Since long lines are necessary, you may want to put an additional diode· from the collector to the emitter (cathode on collector) to protect it from line ringing.
Best of luck!
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Basic stamp Newbie
Post Edited (Hulk) : 2/15/2005 3:52:01 PM GMT
I've attached a circuit that JonW sometimes posts for those wanting to connect a relay to a stamp.
The circuit referenes connecting to Vdd as the source in the tree...so, based on that you might look for a 5V relay....
but if you are using a separate supply for the motors (12V) then maybe automotive relays will be fine.· It's the transistor that will switch the 12V side for you.· This would totally separate your supplies, which is nice....the 2N2222 is a nice transistor to use and a 1N4004 (I think..always confused with the 1N4001) should be fine across the coil.
because you're running a motor, I'd say DEFINATELY separate the supplies.· Of course, you MIGHT need the grounds to be common (odds are yes) in which case you may have some noise bleed back from the motor...it happens, but can be dealt with later.
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Steve
http://members.rogers.com/steve.brady
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
I am recommending the automotive 12V relays because they are very sturdy. The NC contacts in the circut shown above are the weak link. They take an awsome beating during dynamic braking. I'm not sure of any other relays that will stand up to it. I have lab test time on the above so I can propose it without fear.
The dynamic brake can be avoided with some circuit modification, but I think he'll like it to give some precision to the full open and full closed door position.
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Basic stamp Newbie
Having said that, there should be no problem setting the 'Vdd' in the diagram to 12 volts, while the BS2 is driven by +5. Make sure the BS2 Vdd is NOT set to +12, though, that would destroy the BS2.
I'm using a Mercedes window lift motor powered by a 12V 5Ah SLA to operate the slider. I have it connected to the slider with cables and pulleys to open and close, and it works fine!
The battery is "continuously" float charged with a 750mA fully automatic battery tender.
I couldn't find SPDT 40A automotive relays in town, so I'm using 4 SPST 30A automotive relays instead.
Attached is the schematic I adapted from Hulk's recommendation. Before I finish wiring it up and frying by Stamp (or dog), I was hoping I could get some feedback and some questions answered ...
- Have I got it wired up so it will work?
- I've changed the 470ohm resistors to 220ohm because my Stamp comes mounted on the "HomeWork Board" and the manual shows that with this board all pins are already protected with 220ohm resistors (so I figured 220+220 was close to 470). Is this OK?
- In place of the momentatry SPST NC switches Hulk recommended, I'm using momentary SPDT roller microswitches for S1 and S2, with the NC configuration used to energize the relays as in Hulk's design. I'd like to use the NO pin as input to the Stamp, to detect full open and full close of the slider. Will this work? What goes in between the switches and the pins on the Stamp to accomplish this?
- With the HomeWork Board, I have 3 voltage sources available that I could use for V+ and V- in the circuit to energize the relays. Which should I use?
a) 12V from the SLA battery that is powering the motor
b) 9V Vin from the small 120VAC/9VDC adapter that is powering the HomeWork Board (it replaces the 9V battery on the board)
c) Vdd and Vss from the on-board LM29366
- Do I need to tie the 12V ground to Vss? Since these appear as separate circuits in the schematic, it seems that I don't need to if I don't use the 12V to energize the relays, as in a) above
Thanks again for all your help.
You know you'll need to be VERY careful what order you enable (turn-on) the relays, and what sets of relays you turn on at the same time, or you'll get a dead short across your 12 volt supply. You might want a 20 amp fuse in there, just in case.
Thanks. Yeah, it probably looks funny, 'cause I've never seen an H bridge, just tried to extrapolate from Hulk's schematic.
I figured I needed to be 110% sure on the order of firing the relays, but I took your advice and bought a fuse.
I could still us some answers before I connect any power to the controller. (I'm a little nervous about frying the Stamp.) I've attached my updated schematic.
I would feel better if someone could verify that the HomeWork board has the 220 ohm resistors on all pins (not shown on my schematic) and that I should reduce the resistors in the circuit to 220 instead of the original 470 ohms suggested by Hulk.
Also, I've added resistors R1 and R2 between the switches and V- so I can detect switch closure with the Stamp. Is this right? Is 10Kohms appropriate for these? I haven't added a resistor in the lines to the Stamp (again, because of the assumption that the pins are protected by resistors on the HomeWork board). Is this OK too?
I still need some help in selecting V+ and V-. I'm afraid that Vdd and Vss may not be enough to power the relays. Can anyone comment on this? Or, tell me how much the automotive relays draw? And, if they have a minimum voltage requirement?
What about the 9V powering the HomeWork board; would this work for the relays? I can get small 9V supplies at 300mA, 800mA, 1200mA, and 1500mA. Will this be safe to be used as the inputs to the Stamp on P5 and P6?
Or, should I use the 12V from the 5Ah SLA battery? Would this be safe for the Stamp?
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Steve
http://ca.geocities.com/steve.brady@rogers.com/index.html
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
If you want to use +12 (and if those really are automotive relays, then they probably need 12 volts), then P5 and P6 should have a 22 Kohm resistor in series to the pin. The BS2 has 'protection diodes' in the input pins (inside the PIC chip) which will 'clip' any signal over +5 to the BS2. These are normally used when recieving 'raw' RS-232 (+-12 volts) and work fine as long as the input current is limited by a 22 Kohm resistor. Keep the 10Kohm resistor in the 'Ground' leg -- that will pull the signal to zero when the +12 is not enabled.
And don't mind Steve_b's "-V" comment -- if you were an electrical engineer with lots of experience, or this was an op-amp design, this would imply a dual voltage. As you are building a prototype, and it's YOUR schematic after all, and you're not using an op-amp, -V can be ground.
I don't know what relays you are using. They may or may not need a resistor in the 'collector' leg of the transistors. If they really ARE Autmotive relays, they probably don't need a resistor. You might populate the circuit with JUST ONE relay, and measure the current through it and voltage across it when energized. This value is very important -- if it's too high, you may need TIP120 darlington transistors to deal with it.
The 220 ohm / 470 ohm resistors on the base legs of your transistors are to limit the base current. The way a transistor works is as a current device. Current going into the base enables lots of current to go into the collector -- and both currents exit through the emitter. The multiplicative factor is called Hfe, and varies based on what part you've selected.
For digital purposes, we want to 'saturate' the transistor, so it is firmly in the 'on' state. I don't know what transistor you are using, nor its Hfe. These are the critical pieces to know if the base current enables enough current to switch the transistor fully 'on'.
But, the bigger question for me is what it's actually connected to. I gather from the discussion that using the 12V battery to drive the relays is OK, so I've shown the positive terminal of the battery connected to the full-open/full-closed switches (S1 and S2).
As I understand it now, I want to tie all those GNDs to the ground (minus, common, black) terminal on the battery, AND to Vss on the HomeWork board. What about to the ground of the 9V power supply powering the HomeWork Board?
I've added the other resistors according to what I think I got out of your note. Please let me know if I got it backwards.
The relays were purchased at an auto parts store. They are labeled "Heavy Duty Relay", model DF005, either by Federal Mogul or Blazer Intl Corp, and are rated at 30A. I believe they are really "automotive" relays.
If anyone has any last minute warnings, now's the time! I hope to fire it up tomorrow evening.
Thanks, again for all your help.