stupid question from newbie

Archiver

Hello,

I have a question which is probably pretty stupid, but I'd greatly
appreciate some assistance.

When I set a pin on the basic stamp D high, it outputs 1.5 volts.... it's
been a couple months since I've worked on a basic stamp, but it seemed to me
it outted 5 volts previously... it's not enough current to trip my 5volt
coil relays... if the 1.5 volts is natural, can someone tell me how to
boost it to 5-6 to trip my relay? I'm powering the stamp with a 9vdc ac-dc
adapter.

Thanks!
Ben

Archiver

Hi Ben,

If you disconnect everything from the Stamp pin, it should go back to 5V.
You are probably drawing more current than the pin can deliver and therefore
the voltage is being reduced.

Another alternative is that you might have blown that particular output by
drawing too much current, or connecting a coil relay without a reverse
protection diode. Read the other relay post this morning and the Stamp FAQ
at http://www.al-williams.com/wd5gnr/stampfaq.htm


Regards,

Al Williams
AWC
* Control 8 servos at once: http://www.al-williams.com/awce/pak8.htm


>

---

Original Message

---

> From: Ben Wampler [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=wMihheloHFwA7gDM17cKlG9leVKgnX0PEIrI34LM4mPOMykgINYTlGL2S64ksOAfy1GuN90rn1U]bens@e...[/url
> Sent: Thursday, February 15, 2001 11:55 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] stupid question from newbie
>
>
> Hello,
>
> I have a question which is probably pretty stupid, but I'd greatly
> appreciate some assistance.
>
> When I set a pin on the basic stamp D high, it outputs 1.5 volts.... it's
> been a couple months since I've worked on a basic stamp, but it
> seemed to me
> it outted 5 volts previously... it's not enough current to
> trip my 5volt
> coil relays... if the 1.5 volts is natural, can someone tell me how to
> boost it to 5-6 to trip my relay? I'm powering the stamp with a
> 9vdc ac-dc
> adapter.
>
> Thanks!
> Ben
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>

Archiver

Ben,
Remove your relay, set the pin as an output, and set it high. If you still
have 1.5 volts ..... sounds like you lost that pin. This can happen (as has
been mentioned) when you try to drive a relay directly without a back-emf
protection diode.
I hope that's not the case for you. If you do see the output return high,
run the relay directly by putting it across a 5 volt power supply. If this
works, put a multimeter in series with the relay (in current measuring
mode) and connect it to the 5 volt power supply again. The relay shouldn't
draw more than 20 mA at 5 volts (250 ohms). If it does, you've got to drive
the relay through an extenal driver (transistor, mosfet, ULN-2000 series
device.)
I'm kind of an old fashion guy and remember when early digital multimeters
and the needle my old Simpson 260 wouldn't tolerate a large spike. I'd
suggest that even when people are just testing their relays, they should
have the diode in place.
Off my soapbox and back to work.
Mike

At 12:55 AM 2/16/2001 -0500, you wrote:
>Hello,
>
>I have a question which is probably pretty stupid, but I'd greatly
>appreciate some assistance.
>
>When I set a pin on the basic stamp D high, it outputs 1.5 volts.... it's
>been a couple months since I've worked on a basic stamp, but it seemed to me
>it outted 5 volts previously... it's not enough current to trip my 5volt
>coil relays... if the 1.5 volts is natural, can someone tell me how to
>boost it to 5-6 to trip my relay? I'm powering the stamp with a 9vdc ac-dc
>adapter.
>
>Thanks!
>Ben
>
>

Mike Walsh
walsh@i...