Is there a way to get 7volts?

Angela1

Is there a way to make the Vin pin·operate like a I/O pin?

I want to·make a program that turns the Vin pin·"low" or·"high" like I can do for the p1-10 I/O pins. I need to do this or either increase the voltage of one of the P1-10 pins through a 741 op amp. But the 741 needs a V- and I can't get that part.

Any help would be greatly appreciated!!!

Phil Pilgrim (PhiPi)

No, you can't turn Vin into an I/O pin. Why not use an LM358 instead of the 741? You wouldn't need a negative supply, and it will run on a lower positive supply voltage than the 741.

BTW, what do you need the higher voltage for? If it doesn't need to source a lot of current, you could also use a simple open collector transistor inverter.

-Phil

Angela1

Phil Pilgrim (PhiPi) said...
No, you can't turn Vin into an I/O pin. Why not use an LM358 instead of the 741? You wouldn't need a negative supply, and it will run on a lower positive supply voltage than the 741.

BTW, what do you need the higher voltage for? If it doesn't need to source a lot of current, you could also use a simple open collector transistor inverter.

-Phil

Thanks for you patience, Phil...·The point you tried to get across to me had a little delay reaction (like z^-3432) b/c·my brain takes a little time to chic-a-chic-a.... and then...

I checked out the datasheet for the LM358 and started grinning. Its exactly what I need. I plan on going to radio shack and getting their·LM324 and LM339 tomorrow (remember to always call them first ). Oh yeah, thanks for confirming that the Vin can't be operated like an I/O pin.

In theory... ... the op amp's output·will be used to power a ~7volt remote receiver (checked with voltmeter).

In theory,·the stamp program turns off and on an I/O pin depending on the ping sensor's readings. Then by using the op amp, the I/O pin's voltage will be increased enough to power the receiver, but if the I/O pin is off then the receiver will turn off too because the voltage isn't high enough... i guess it's a really sloppy dead man's switch for designing a... SECURITY ROBOT!!!!

Phil Pilgrim (PhiPi)

How much current does the receiver require? Have you checked to make sure the op amp can source enough current to operate it? If not, there are other ways to do this.

-Phil

Angela1

Phil Pilgrim (PhiPi) said...
How much current does the receiver require? Have you checked to make sure the op amp can source enough current to operate it? If not, there are other ways to do this.

-Phil

... Phil... what other ways are there to do this...

Phil Pilgrim (PhiPi)

Assuming your receiver draws around 100mA or less (and you haven't stated yet what its requirements are), this circuit will do the job:



It will drop about a volt from input to output. If the receiver requires a regulated 7V (again, you haven't specified this), you may want to up your supply voltage to 9V or more and add a voltage regulator after the transistor siwtch.

Your first task, however, is to determine exactly what the receiver's power requirements are. This will help in coming up with the correct circuit.

-Phil

Angela1

Phil Pilgrim (PhiPi) said...
Assuming your receiver draws around 100mA or less (and you haven't stated yet what its requirements are), this circuit will do the job:



It will drop about a volt from input to output. If the receiver requires a regulated 7V (again, you haven't specified this), you may want to up your supply voltage to 9V or more and add a voltage regulator after the transistor siwtch.

Your first task, however, is to determine exactly what the receiver's power requirements are. This will help in coming up with the correct circuit.

-Phil

Thanks Phil for your time helping me... I·seriously appreciate it because this project has been a bit stressfull at times...

Ok, power requirements... well the stamp pin I chose generates 5V, the supply is a 9V battery pack and the receiver is 9V but it was doing ok at above 7V. I tried to find the required current for the receiver but it seems to not be given...

Angela1

Phil Pilgrim (PhiPi) said...
Assuming your receiver draws around 100mA or less (and you haven't stated yet what its requirements are), this circuit will do the job:



It will drop about a volt from input to output. If the receiver requires a regulated 7V (again, you haven't specified this), you may want to up your supply voltage to 9V or more and add a voltage regulator after the transistor siwtch.

Your first task, however, is to determine exactly what the receiver's power requirements are. This will help in coming up with the correct circuit.

-Phil

Phil... give me your address because·I want to send you a thank you letter... the circuit works yaaaay!!!...·unfortuantely, it doesn't carry enough power to operate the wheel servos. But I am pretty·sure (99%)·if the voltage was higher then it would work going based on a light on the reciever that indicates when theres·not enough voltage and by experimenting with it with the pins.

The light flashes when I connect·a·5 volt generating I/O pin to it (I predict it's telling me the power isn't sufficient),·but·it·becomes·fully operational·when ·I connect it directly to the Vin which gave me 9V but I can't turn off and on the Vin like a pin·(why I asked that one question), and with your circuit it produces·enough voltage to keep the light indicator on! but it starts flashing again when I·moved the joystick. So it's right in the middle it seems.

But it resets the voltage to zero which is sweet! Thank you for that.·Could you tell me if I changed·the resistor ratio, will the voltage·increase to supply the receiver? Or should I·use a higher 2nd power supply voltage than a 9V battery in order to increase the output voltage for the receiver? I used one 9V for the stamp board's power supply and another 9V battery as the second battery supply or was I supposed to use the same battery supply? Thanks again.

Phil Pilgrim (PhiPi)

Okay, you didn't mention having to power servos, too. The 2N2906 simply won't do the job. For that, I would recommend a pMOSFET, like the 2SJ412. Referring to my original schematic, the following are equivalent for the 2SJ412Q-2N3906 replacement: source-emitter, gate-base, drain-collector. Also, remove the 1K resistor.

-Phil

Angela1

Phil Pilgrim (PhiPi) said...
Okay, you didn't mention having to power servos, too. The 2N2906 simply won't do the job. For that, I would recommend a pMOSFET, like the 2SJ412. Referring to my original schematic, the following are equivalent for the 2SJ412Q-2N3906 replacement: source-emitter, gate-base, drain-collector. Also, remove the 1K resistor.

-Phil

Sorry for not adding that part. I have CD4007UBE·n&p channel MOSFET IC. Will that work instead? I am kinda scared of ICs now because of the V- problem I had so I was hoping to avoid it... but do you think I could use the CD4007UBE·instead and using it's pin layout to fit into the original circuit???... and also taking out the 1k resistor?

mechano

hi every body

ok you are giving many solutions for his problem but there is one thing i didn't see it yet in all the post above

it is very easy to use electrical contactor (Relay) working with DC volt and there are many types like this and can

work directly from the signal of I/O of Basic stamp, after that use the contacting pins as you wish

i think this is very simple solution and very cheap also

any further information regarding this matter i'm ready

by the way for any electronic circuit you can check (www.4shared.com) or (www.gigapedia.org) you can find many

electronic books, download it and search in it

regards

Phil Pilgrim (PhiPi)

The CD4007 would definitely not work. I agree with mechano: a dry-contact relay may be the simplest and quickest thing you can do with readily-available parts. See the FAQ at the head of this forum for a working circuit.

-Phil

Angela1

Phil Pilgrim (PhiPi) said...
The CD4007 would definitely not work. I agree with mechano: a dry-contact relay may be the simplest and quickest thing you can do with readily-available parts. See the FAQ at the head of this forum for a working circuit.

-Phil

Ok I'll try to get the 2SJ412Q and see if that works! And I'll try the relay circuit too! I'll try anything!! lol Thanks again Phil for the help. A FAQ?·· Umm.... where/huh is it?

Angela1

mechano said...
hi every body

ok you are giving many solutions for his problem but there is one thing i didn't see it yet in all the post above

it is very easy to use electrical contactor (Relay) working with DC volt and there are many types like this and can

work directly from the signal of I/O of Basic stamp, after that use the contacting pins as you wish

i think this is very simple solution and very cheap also

any further information regarding this matter i'm ready

by the way for any electronic circuit you can check (www.4shared.com) or (www.gigapedia.org) you can find many

electronic books, download it and search in it

regards

hi mechano, you mentioned an "easy" lol and "cheap" way of doing this. Yes, please help me. Further information is very much desired on my side.

Phil Pilgrim (PhiPi)

The FAQ is here: http://forums.parallax.com/showthread.php?p=783327.

-Phil

StormKing09

as for getting 7VDC, I'd probably just get a mini transformer to up the voltage

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Angela1

Phil Pilgrim (PhiPi) said...
The FAQ is here: http://forums.parallax.com/showthread.php?p=783327.

-Phil

Phil, I am trying to find a "transistor driver" online but I can't find any venders or any hits on this. Do you know the part number by chance?

vaclav_sal

It seem you have some misconception about transformers - they do not work with DC.

Phil Pilgrim (PhiPi)

A "transistor driver" is just a transistor that's being used to drive a load. In the FAQ, it refers to the 2N2222 that's being used to drive the relay coil. Which transistor you choose will depend on how much current the relay coil requires. Here is a relay whose coil will operate from 18mA at 7.9VDC. The contacts are rated at 12A, which should be plenty for your servos. You can drive the coil with a 2N3904 transistor through a 1K or so base resistor. A 1N4003 diode across the coil will be adequate protection.

-Phil

Angela1

Phil Pilgrim (PhiPi) said...
A "transistor driver" is just a transistor that's being used to drive a load. In the FAQ, it refers to the 2N2222 that's being used to drive the relay coil. Which transistor you choose will depend on how much current the relay coil requires. Here is a relay whose coil will operate from 18mA at 7.9VDC. The contacts are rated at 12A, which should be plenty for your servos. You can drive the coil with a 2N3904 transistor through a 1K or so base resistor. A 1N4003 diode across the coil will be adequate protection.

-Phil

Phil, your like my best friend! Thanks for the links because the coil component honestly had me @_@... your explanations always make sense.

Angela1

Phil Pilgrim (PhiPi) said...
A "transistor driver" is just a transistor that's being used to drive a load. In the FAQ, it refers to the 2N2222 that's being used to drive the relay coil. Which transistor you choose will depend on how much current the relay coil requires. Here is a relay whose coil will operate from 18mA at 7.9VDC. The contacts are rated at 12A, which should be plenty for your servos. You can drive the coil with a 2N3904 transistor through a 1K or so base resistor. A 1N4003 diode across the coil will be adequate protection.

-Phil

Hey Phil, can you help me again? I wanted to know if I needed any other components for this circuit using a 7-9V relay. Do I just need the NPN trasistor, the relay, a 1k resistor, and a diode? I am trying to build the circuit and not getting the right results.·Halp!

Phil Pilgrim (PhiPi)

That's all you need. Did you follow the schematic in the FAQ?

-Phil

knightofoldcode

Angela,

I would strongly suggest you read the Nuts and Volts column #6. It explains exactly why the diode is there, what it does, and how to change things if needed for different circumstances, etc, etc, etc.

Electronics is part of learning... sure it's great to have a schematic given to you, but it's also great to know how to make that schematic.

Read the mentioned column, if you have any more questions, I'm sure people would be willing to answer them.

Go to this link: www.parallax.com/Portals/0/Downloads/docs/cols/nv/vol1/col/nv6.pdf



In the future you might want to look up other nuts and volts columns... just go to the main parallax webpage, click "resources" tab, then click on the "Nuts and Volts" columns. They are all there for free... they are EXCELLENT learning tools! In fact, so much so that I have downloaded EVERY LAST ONE, and compiled them all into a single PDF. Then when I have a chip I want to play with I will do a search for that chip in the large single PDF. It works great to show me if they have the chip, or if they have a tutorial on the chip.


Knight.

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This message transmitted with 100% recycled electrons.
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Gravity doesn't exist. The Earth sucks.
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Make a man a fire, and he will be warm for the night.
Light the man on fire, and he will be warm for the rest of his life.
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Angela1

Phil Pilgrim (PhiPi) said...
That's all you need. Did you follow the schematic in the FAQ?

-Phil

Yeah, I tried·to follow the schematic but there was a lot of·additional·parts that had me confused when I got the relay. But I tried to follow it. Like, instead of using the stamp I/O pin I substituted it for·the transistor cicuit's output of 7.5V. Then I used a 5V I/O pin·for the above contact... but I wasn't to sure what to use for the "com" which was for the section of the armature inside the coil... then there was the normally closed and open contacts... I connected my new output to the normally open setting·for when·the armature moves up. So I only had three connections for the relay... Little confused again... I tried looking up tutorials on relays but none really were any help... or is it the top part which is the output I am looking for? Like in the schematic there was the +5 in a circle? Maybe that it what it is...· reply soon!

Angela1

Phil Pilgrim (PhiPi) said...
That's all you need. Did you follow the schematic in the FAQ?

-Phil

Oh my goodness! I think·I got it·figured out! Unfortunately, I broke the armature like you warned because I was so happy that I may have crossed the line of "playing with" the relay... and consequently ended up breaking it. Another trip to radio shack *sigh*... thanks again·Phil for the help and hopefully you wont mind if I give you a holler if I come across any other problems...

Angela1

knightofoldcode said...
Angela,

I would strongly suggest you read the Nuts and Volts column #6. It explains exactly why the diode is there, what it does, and how to change things if needed for different circumstances, etc, etc, etc.

Electronics is part of learning... sure it's great to have a schematic given to you, but it's also great to know how to make that schematic.

Read the mentioned column, if you have any more questions, I'm sure people would be willing to answer them.

Go to this link: www.parallax.com/Portals/0/Downloads/docs/cols/nv/vol1/col/nv6.pdf



In the future you might want to look up other nuts and volts columns... just go to the main parallax webpage, click "resources" tab, then click on the "Nuts and Volts" columns. They are all there for free... they are EXCELLENT learning tools! In fact, so much so that I have downloaded EVERY LAST ONE, and compiled them all into a single PDF. Then when I have a chip I want to play with I will do a search for that chip in the large single PDF. It works great to show me if they have the chip, or if they have a tutorial on the chip.


Knight.

I read it! I mean, I read it after you gave me the link. lol. I definately will check out the columns in the near future. Thanks, it clarified a lot!