- #1
Adder_Noir
- 239
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Hi!
Please forgive me but this is the dodgiest circuit drawing ever made by anyone ever anywhere but I only had MS paint to hand![Smile :smile: :smile:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
http://img514.imageshack.us/img514/3940/dodgyelectronicspic.png
It's a circuit which I want to use to make a small power circuit pulse at max voltage a variable number of times over a set time period. Basically instead of varying the voltage through the load I want to keep the voltage maxed but vary the time it is present for.
My idea is to use a variable resistor in an R-C arrangement to cause a capacitor to build up above the voltage required to overcome a zener diode and then activate a transistor input to allow current through the load briefly before the capacitor discharges enough to allow the the zener to stop it driving current again and then the cycle repeats.
I have 2 questions:
1) Is the circuit design good enough to allow the transistor to turn fully on for long enough or will the voltage constantly oscillate around the zener voltage causing the transistor to flutter on and off too quickly/weakly?
2) Is it possible to get a suitable power transistor to work in this fashion or am I asking too much of a transistor here? Will I have to combine it with an op amp or something to get it to work properly? The load in this case is a small model railway engine which takes 12 volts.
Thanks! ;)
Please forgive me but this is the dodgiest circuit drawing ever made by anyone ever anywhere but I only had MS paint to hand
http://img514.imageshack.us/img514/3940/dodgyelectronicspic.png
It's a circuit which I want to use to make a small power circuit pulse at max voltage a variable number of times over a set time period. Basically instead of varying the voltage through the load I want to keep the voltage maxed but vary the time it is present for.
My idea is to use a variable resistor in an R-C arrangement to cause a capacitor to build up above the voltage required to overcome a zener diode and then activate a transistor input to allow current through the load briefly before the capacitor discharges enough to allow the the zener to stop it driving current again and then the cycle repeats.
I have 2 questions:
1) Is the circuit design good enough to allow the transistor to turn fully on for long enough or will the voltage constantly oscillate around the zener voltage causing the transistor to flutter on and off too quickly/weakly?
2) Is it possible to get a suitable power transistor to work in this fashion or am I asking too much of a transistor here? Will I have to combine it with an op amp or something to get it to work properly? The load in this case is a small model railway engine which takes 12 volts.
Thanks! ;)
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