pwm
I've been trying to follow an example circuit that does some PWM. First I believe that in a configuration something like this with nor & and that the wave should alternate. Violet line is pulsing 5-5V as I needed to happen. Green is a flat line. I need green to alternate with violet and the lamp on the green line I want it to light up along with the lamp on violet.
I have to have made mistake. Does anyone see what's wrong. I've been trying for while on this.
Thank you
You can try buffering the output of the filter with a pair of darlington emitter-followers, which will replace the four diodes with four transistors.
simulate this circuit – Schematic created using CircuitLab
You can try buffering the output of the filter with a pair of darlington emitter-followers, which will replace the four diodes with four transistors.
Check that the no-load bias current in the output transistors is not too high.
It might be easier to use an op-amp though, if you can get some that are suitable.
When using paralleled MOSFETS in the output stage as you are, your should install small ballast resistors (0.2 Ohm) on each source terminal to ground. This will ensure that the MOSFETs share the current equally.
...The way this works is if one MOSFET starts taking more of the current, this will lead to a lowering of the Vgs of that MOSFET which turns the MOSFET off slightly and re-balances the current between MOSFETs.
Also, its best to give each MOSFET its own independent gate resistor, this can eliminate any potential oscillations (at least thats recommended in amplifier circuits with paralleled output transistors).
Best Answer
I've never heard of EveryDay Circuit but wow do they ever constrain you. They give you no space at all. I managed to model it for you but theres no place to really add any resistors because I think my lamps were catching fire.
I've made the schematic here as well. You can run the simulation from here and see how it works.
When SHUTDOWN is 0, the AND gates output zero. When SHUTDOWN is 5V, the HIGH follows the input signal When SHUTDOWN IS 5V, the LOW follows complimentary of the input signal because of the NOT gate.
The resistors are just there to limit the current for the LED.