Kwinn,
I am drawing up the prototype for one of the relay slaves. I will be using my two sample tpics, the sample driver and receiver and 16 of the relays. I think i have everything covered as far as placement. I know I need a cap between the vcc and gnd of the drivers and receivers, do I also need it on between the vcc and gnd of the tpics?
Any other places I need to put resistors or capacitors in the system aside from on the led's?
I ran into a problem with my CNC last night and·smoked two of the driver chips so it will be a week until the replacements show up.· I did some testing with my PCB artist software and my CNC software and as far as I can tell, the export from one to the other works great and the simulation I ran with the CNC control showed it would be drilling in the correct locations so I'm getting somewhere finally.· I have new drive screws and some upgrades on the way for the cnc, but hopefully next week I can have the prototype working for a relay slave. ·
Best to put a cap between .01 and .1uF as close as possible to the power and ground pins of every chip. I have been reading your CNC thread and was sorry to hear you were having problems. Glad to hear you are making progress.
This may be a dumb question, and I'm pretty sure I know the answer is yes, but anyway, is ground always a common ground, even if it is coming from different sources. For example. Can I have the +5v grounded to the same place as the +24v on the boards, or do they need to be seperate for some reason? The reson I'm asking is on the relays, I have a common ground for the +5v for the relays to activate, I want to put a LED in to show if the relay is actually on. The 5v ground runs right next to where it would be convenient to ground the led's to off the +24 that is going thru the relays when they are on. Does that make sense?
they usually are grounded together. If using separate power supplies depending on your schematic you may not have to though. In your case though you probably want your grounds to be common at one point(where your power lines come into the board) and then from that point on keep the high current ground separated from the digital ground.
If you have high current going through traces it can raise the voltage of the ground along the trace causing digital ic to have a smaller voltage differential. It can also produce heat and magnetic noise.
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In most cases all the power supply grounds are connected together at some point. In your case I am not sure if this is a good idea. It depends on how you plan to power the master and slaves and the actual currents involved. Have you made a decision on that.
As of right now the plan is to use power coming off a master power box for 5v and 24v running across a 18/4 cable to all of the slaves. The master console will have it's own 5v power supply for the drivers and prop chip.
I drew up an example of what I'm talking about, the 24v that will piggyback on the 5v ground will be very low current as it is only going thru a resistor and LED.· The main 24v ground will still come back to the main ground point.
Could I have a seperate 24v and 5v ground and have a capacitor or resistor or something in between them so I can safely use the 5v ground for my status LED's
Chaosgk, my concern is not with the current the leds draw, but the current pulse produced when the relay closes to ignite the charge. If that is a big enough pulse it may affect the 5V logic circuits and possibly change the state of the TPIC's. The only way to be sure is to build the prototype and try it, but it would be a good idea to be able to connect or keep the grounds separate. Use a jumper to connect the 24V and 5V grounds together, and connect all the led common connections together and use a second jumper to connect that to the 5V or 24V ground.
another possible concern is #18 is not very big. how long a cable are you using to power supply? if long then there will be a significant voltage drop across it while firing if short not a problem. can't remember if supply was controller side or relay side
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The main power board is going to be out in the field with the slaves, the runs to each of the slaves from the power board/box will be 50-100 feet. In the past we have pushed 12v to the igniters across 24awg wire without problem. We've pushed those well over 600' with instant ignition. Remember the igniters are similar to a christmas tree twinkle light for power requiremets to get them to light up.
I'm not really sure if I can design the board to have a jumper for linking the grounds the way I want. I was going to use the relay ground because there is currently open space between the relays that would fit a LED and resistor pair coming off the closed 24v feed of the relay and that could connect directly to the 5v relay ground. I'm trying to avoid as many vias as I can on the boards to simplify the soldering of all of this stuff. I would think it would be ok, but i'm not an expert so I will just have to try it. Any other suggestions on how to accomplish this. I will be posting my PCB design late tonight when I finish it for your approval before I etch the first prototype. Anything that you guys know of that works really well for jumping over traces aside from a simple piece of wire and a couple of holes on either side of the trace i need to cross and solder it in place or use a via and route it to the back side of the board?
Ok, say for example, I activate a relay without it being connected to an igniter. The current will pass thru the resistor, thru the led and into the ground, is it this pulse from the relay that is a problem or from the relay turning off when the igniter is hooked up. If it's the first one, couldn't I use a diode in between the 5v and 24v ground so the 24v pulse from the relay kicking off wouldn't transmit to the 5v, but the 24v going thru the LED would have a path back to 24v ground? That almost doesn't make sense in my own head, hope you get what I'm thinking. Basically I'm looking for a simple way to see if a relay is turned on without actually having the ignitors hooked up so I can run thru a program and see the relays activate in sequence. It may be overkill, but it would be nice to know ahead of time if a relay is hot before I plug some thing that is going to explode into it. This way if we run the show and come back to use it again next year, we will know if any of the relays welded themselves shut and need to be replaced.
the problem is the voltage drop raising the ground plane voltage.
100' has resistance of 0.63850
at 2amp your ground plane would be 1.3v higher leaving the 5v rail only 3.7v left
a nice clean way to jump traces would be to use 0 Ohm resister 1206 size is fairly large and requires no holes.
usually they are only good for low current though
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if you have a separate ground path for the 24v stuff and another for 5v as long as the 5v side is low current(.3 amp or less) you will probably be ok only
0.63850*2*current drop in voltage for digital side. may want to consider buck boost converter to regulate on slave side
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Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
Ok guys, here is the prototype PCB Design.· I used pcb artist at www.pcbartist.com to design it.· I have uploaded both the project and a JPG of it, I had to create some custom components to match my relays and a couple other things so I included that with as well.·
You should be able to figure out what most of it is. Please check my track layouts and see if I missed anything.· I really hope it is easier for you guys to follow then it was for me to create.· If this works, the real slave boards will be the same thing except scaled up and different connectors for the RJ45's.· I also don't have the ground included in the cat5 outs since it is a prototype I was only concerned with getting all 8 outputs from the tpics routed somewhere.
The contents of relay.zip came from C:\Documents and Settings\All Users.WINDOWS\Documents\PCB Artist\Library.
You shoudl be able to extract them·to anywhere and in the software go to File>Libraries and browse to where ever you extract them to.
I will be busy most of saturday and sunday with other stuff so won't have much time to check back in.
Chaosgk, I am having some trouble interpreting your schematic, so I have made a quick sketch of one relay with the connections to the TPIC, power supplies, and igniter. Forgive me if I am stating the obvious, but I would rather do that than have you waste a lot of time miswiring the board.
Ok, I think we are on the same page, the only question I have is coming off the relay coil it shows +5v for relay coil. Is that after it has gone through the coil on it's way to ground? ·
the way he has drawn it you would send a 0 out to pull in the relay conecting ground through the ic. the reason for that is most ics can handle more power draw to ground then to the voltage rail.
don't forget the diode in reverse acrose the relay coil.
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Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
Side one of the relay coil goes to +5V and side two goes to the TPIC. The output transistor in the TPIC will connect side two to ground when activated.
As mctrivia pointed out a diode is needed as he added to the schematic.
Oh.. I was thinking the other way around, I thought the tpic would be providing the +5v to the relay coil and the other side would be going to ground. Good to know.. That's why I have you guys double checking my work. What is the purpose of the diode across the relay coil? I haven't heard of that in the plans before.
I know nothing about diodes except LED's and that they act as one way valves for the current. What size and type of Diode do I need there?
No, you don't need to add the diode. It is already built in to the TPIC. Been so long since we started this thread I forgot that. Also should not answer posts when I am dead tired. The devil really is in the details.
I know nothing of the TPIC. The reason for the diode is when you take power away from a coil as the magnetic feild collapses it induces a voltage of equal current in the oposit direction. The diode shorts this reverse voltage out protecting the rest of your circuit.
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Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
Ok, so we are good on the original drawing by kwinn?
Kwinn, can you draw up a quick schematic of my connections into the prop board and anything special I will need on that since my prototype board will be useless without it? I'm planning on doing the master board in one shot. I will only solder on the first driver and use it for testing, but I may as well draw up the entire thing and print the board.
I just picked up a nice color laser printer from my work for cheap for home so I can print all of my boards here instead of using the lasers at work. I'm having trouble with my drawing program, it's printing all of my traces as giant scale and all of the chips as the correct size so they all overlap.
Damn computers.
save some room in your design for a buck/boost for the 5v rail.
depending on cable lengths you may not need but if you chop the end off my propmod you can keep only the last 4 pins on each side and use it as a 1.8V-5.5V in to 5V out converter. If you need it I will supply 4 boards free. If you do not need it you can just place a jumper wire between input and output.
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Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
I have attached the slave schematic and it has all the connections to the prop on it. I am assuming that we are not trying to conserve prop pins by adding extra slave decoding chips. If you want more than 8 slaves they would be wired the same as the first 8 with the connections to P0 to P3 and P12 being identical, and using P13 and up as the select lines for each driver. Let me know if you have any questions.
Ok, just so I'm clear on reading this, p0,p1,p2,p3 and p12 are the same across all drivers. Drivers only need the voltage and ground into them and then they go from the outputs to the RJ45's keeping the pairs together, into the drivers. No other resitors or caps needed (except the cap across the vcc and ground near the driver).
Can I put a LED on the drivers somewhere to see when they are on or active?
if you haven't noticed, I love seeing flashing lights on electronics.
Anything special I need to do to the prop board aside from maybe put a pin header on so I can connect it using a ribbon cable? ·
you can put low current led on all digital lines as long as they are not really high frequency or already loaded down by running multiple ics of the same trace. you can always put the holes in for the resister and led. try first without the led in if works try with in. remove if you have any trouble.
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Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
Do you have a good way to insulate the board after the traces have been etched, some way that I can leave just the holes open and cover the rest of the traces. I was thinking of maybe putting on a thin layer of clear coat and then put a wire brush attachment in the cnc and have it go back and brush the locations, or instead of washing the toner off when it is done etching, leave it in place and use the same method with the cnc and brush to have it buff the toner off, then run through the drilling process, or drill then buff. I'm not sure if I can find a soft wire brush that small or what I would need or if I would have to make something, but I would like the traces somewhat insulated and I think the toner may work just fine.
you can buy solder mask in a past and pen format. Same stuff they put on professionally done boards. Don't have a link I buy locally.
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Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
Not exactly the same but you can put it on then brush or cut out the sections you want exposed.
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Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
Yes, as drawn on the schematic P0, P1, P2, P3, AND P12 are common to all the TPICS. If you want to keep all the control signals consecutive we could move the signal on P12 to P4 and have the line driver select signals on P5 and up.
I have used nail polish in an emergency as a solder mask, but it does not hold up well to heat so you have to solder carefully and quickly.
Comments
I am drawing up the prototype for one of the relay slaves. I will be using my two sample tpics, the sample driver and receiver and 16 of the relays. I think i have everything covered as far as placement. I know I need a cap between the vcc and gnd of the drivers and receivers, do I also need it on between the vcc and gnd of the tpics?
Any other places I need to put resistors or capacitors in the system aside from on the led's?
I ran into a problem with my CNC last night and·smoked two of the driver chips so it will be a week until the replacements show up.· I did some testing with my PCB artist software and my CNC software and as far as I can tell, the export from one to the other works great and the simulation I ran with the CNC control showed it would be drilling in the correct locations so I'm getting somewhere finally.· I have new drive screws and some upgrades on the way for the cnc, but hopefully next week I can have the prototype working for a relay slave.
·
If you have high current going through traces it can raise the voltage of the ground along the trace causing digital ic to have a smaller voltage differential. It can also produce heat and magnetic noise.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
I drew up an example of what I'm talking about, the 24v that will piggyback on the 5v ground will be very low current as it is only going thru a resistor and LED.· The main 24v ground will still come back to the main ground point.
Could I have a seperate 24v and 5v ground and have a capacitor or resistor or something in between them so I can safely use the 5v ground for my status LED's
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Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
I'm not really sure if I can design the board to have a jumper for linking the grounds the way I want. I was going to use the relay ground because there is currently open space between the relays that would fit a LED and resistor pair coming off the closed 24v feed of the relay and that could connect directly to the 5v relay ground. I'm trying to avoid as many vias as I can on the boards to simplify the soldering of all of this stuff. I would think it would be ok, but i'm not an expert so I will just have to try it. Any other suggestions on how to accomplish this. I will be posting my PCB design late tonight when I finish it for your approval before I etch the first prototype. Anything that you guys know of that works really well for jumping over traces aside from a simple piece of wire and a couple of holes on either side of the trace i need to cross and solder it in place or use a via and route it to the back side of the board?
Ok, say for example, I activate a relay without it being connected to an igniter. The current will pass thru the resistor, thru the led and into the ground, is it this pulse from the relay that is a problem or from the relay turning off when the igniter is hooked up. If it's the first one, couldn't I use a diode in between the 5v and 24v ground so the 24v pulse from the relay kicking off wouldn't transmit to the 5v, but the 24v going thru the LED would have a path back to 24v ground? That almost doesn't make sense in my own head, hope you get what I'm thinking. Basically I'm looking for a simple way to see if a relay is turned on without actually having the ignitors hooked up so I can run thru a program and see the relays activate in sequence. It may be overkill, but it would be nice to know ahead of time if a relay is hot before I plug some thing that is going to explode into it. This way if we run the show and come back to use it again next year, we will know if any of the relays welded themselves shut and need to be replaced.
100' has resistance of 0.63850
at 2amp your ground plane would be 1.3v higher leaving the 5v rail only 3.7v left
a nice clean way to jump traces would be to use 0 Ohm resister 1206 size is fairly large and requires no holes.
usually they are only good for low current though
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
Post Edited (mctrivia) : 5/1/2009 10:01:19 PM GMT
0.63850*2*current drop in voltage for digital side. may want to consider buck boost converter to regulate on slave side
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Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
You should be able to figure out what most of it is. Please check my track layouts and see if I missed anything.· I really hope it is easier for you guys to follow then it was for me to create.· If this works, the real slave boards will be the same thing except scaled up and different connectors for the RJ45's.· I also don't have the ground included in the cat5 outs since it is a prototype I was only concerned with getting all 8 outputs from the tpics routed somewhere.
The contents of relay.zip came from C:\Documents and Settings\All Users.WINDOWS\Documents\PCB Artist\Library.
You shoudl be able to extract them·to anywhere and in the software go to File>Libraries and browse to where ever you extract them to.
I will be busy most of saturday and sunday with other stuff so won't have much time to check back in.
·
don't forget the diode in reverse acrose the relay coil.
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Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
Post Edited (mctrivia) : 5/3/2009 1:53:51 AM GMT
As mctrivia pointed out a diode is needed as he added to the schematic.
Post Edited (kwinn) : 5/3/2009 3:13:41 AM GMT
I know nothing about diodes except LED's and that they act as one way valves for the current. What size and type of Diode do I need there?
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Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
Kwinn, can you draw up a quick schematic of my connections into the prop board and anything special I will need on that since my prototype board will be useless without it? I'm planning on doing the master board in one shot. I will only solder on the first driver and use it for testing, but I may as well draw up the entire thing and print the board.
I just picked up a nice color laser printer from my work for cheap for home so I can print all of my boards here instead of using the lasers at work. I'm having trouble with my drawing program, it's printing all of my traces as giant scale and all of the chips as the correct size so they all overlap.
Damn computers.
depending on cable lengths you may not need but if you chop the end off my propmod you can keep only the last 4 pins on each side and use it as a 1.8V-5.5V in to 5V out converter. If you need it I will supply 4 boards free. If you do not need it you can just place a jumper wire between input and output.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
Can I put a LED on the drivers somewhere to see when they are on or active?
if you haven't noticed, I love seeing flashing lights on electronics.
Anything special I need to do to the prop board aside from maybe put a pin header on so I can connect it using a ribbon cable?
·
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
https://www.alliedelec.com/Search/ProductDetail.aspx?SKU=6610430&MPN=862-150ML&R=6610430&SEARCH=6610430&DESC=862-150ML
Not exactly the same but you can put it on then brush or cut out the sections you want exposed.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
I have used nail polish in an emergency as a solder mask, but it does not hold up well to heat so you have to solder carefully and quickly.