stamps and SCR''s
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Date: Sat, 13 May 2000 16:40:34 -0400
From: "Chris Loiacono" <chris@a...>
Thanks!. And I'll bet you can save me how many hours with a sentence
or two on how you used the PWM feature?
Sorry for begging, this is my first stamp application.
<<
Ok - the Velleman DC controlled dimmer module has an optocoupler
input - the LED in the coupler doesn't do anything until over
a volt input so I decided to drive it with varying _current_.
Therefore I made a circuit between the STAMP and optocoupler
dimmer input which changed the integrated PWM from STAMP
[noparse][[/noparse]by 10000 ohms and .47 uf to ground] input to an op amp +
[noparse][[/noparse]1/4 LM324] to a proportional current output to the optocoupler.
in-10KR
|+ OptoLED
| | opa >--->|-|----|
.47u |_|- | 330Ohm
.........V-.|______________| 10K ohm pot
.................................V-5v
So: PWM from stamp goes thru 10K R to + opamp in.
.47Uf goes from + opamp in to V- [noparse][[/noparse]PWM filter & hold]
output of opamp goes to driven LED optocoupler + side.
.01 capacitor across optocoupler LED - JIC [noparse][[/noparse]just in case...]
negative side of opto LED goes to - opa input
negative side of opto LED goes to 330 ohms in series with 10K
Variable resisitor to V- [noparse][[/noparse]adjust current sensitivity].
Since the durrent through the LED goes through the 330 ohm + 10K
reostat and this voltage is fed back into the - opamp input it
puts current through the LED proportionate to the integrated [noparse][[/noparse]by
.47uf] PWM signal fromt he stamp.
I hope this helps... the Velleman DC controlled dimmer has some
pots on it to adjust stuff too...
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Date: Sat, 13 May 2000 16:40:34 -0400
From: "Chris Loiacono" <chris@a...>
Thanks!. And I'll bet you can save me how many hours with a sentence
or two on how you used the PWM feature?
Sorry for begging, this is my first stamp application.
<<
Ok - the Velleman DC controlled dimmer module has an optocoupler
input - the LED in the coupler doesn't do anything until over
a volt input so I decided to drive it with varying _current_.
Therefore I made a circuit between the STAMP and optocoupler
dimmer input which changed the integrated PWM from STAMP
[noparse][[/noparse]by 10000 ohms and .47 uf to ground] input to an op amp +
[noparse][[/noparse]1/4 LM324] to a proportional current output to the optocoupler.
in-10KR
|+ OptoLED
| | opa >--->|-|----|
.47u |_|- | 330Ohm
.........V-.|______________| 10K ohm pot
.................................V-5v
So: PWM from stamp goes thru 10K R to + opamp in.
.47Uf goes from + opamp in to V- [noparse][[/noparse]PWM filter & hold]
output of opamp goes to driven LED optocoupler + side.
.01 capacitor across optocoupler LED - JIC [noparse][[/noparse]just in case...]
negative side of opto LED goes to - opa input
negative side of opto LED goes to 330 ohms in series with 10K
Variable resisitor to V- [noparse][[/noparse]adjust current sensitivity].
Since the durrent through the LED goes through the 330 ohm + 10K
reostat and this voltage is fed back into the - opamp input it
puts current through the LED proportionate to the integrated [noparse][[/noparse]by
.47uf] PWM signal fromt he stamp.
I hope this helps... the Velleman DC controlled dimmer has some
pots on it to adjust stuff too...
________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk! For your FREE software, visit:
http://dl.www.juno.com/get/tagj.