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enter image description here

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

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  • \$\begingroup\$ Not sure I follow what you are trying to do. Are you just trying to create a PWM from a sinusoid ? Do you need to vary duty cycle ? Does it need to be implemented with logic gates ? \$\endgroup\$
    – efox29
    Jan 26, 2015 at 8:36
  • \$\begingroup\$ What is your purple line supposed to do ? What is your green line suppose to do ? How are they supposed to work with your sine wave ? Why is there a sine wave there ? Are you just adding it in because you think it would help generate a pwm signal? \$\endgroup\$
    – efox29
    Jan 26, 2015 at 8:53
  • \$\begingroup\$ Thank you for asking. I'm not really feeling particular at all how this gets done but I really like to sim because I'm learning still and I have to pack everything into small space. I thought perhaps my two logic gates might be used in place of my IC an IR2104. So the purple and green lines are the HI and LO pin output for my Half Bridge Driver. According to use principles one can operate LO or HI but never both at the same time. OK. So I would like to alternate a square wave when one is on the other is off. As well after high is on for 100 micros then LO for 100 micros \$\endgroup\$
    – Eae
    Jan 26, 2015 at 9:03
  • \$\begingroup\$ and then an SD which shuts down HI and LO together. I'm noticing my Mosfets the IRLZ24's the gate pin only disables current flow from source to drain but never from drain to source even with very big resistors between its source and gate. \$\endgroup\$
    – Eae
    Jan 26, 2015 at 9:05
  • \$\begingroup\$ I only wish I had the answer right now to the question about CMOS or TTL I only know my mosfets are irlz34 series came with my kit. I would really like to see if my sim will show any current backing up in inductor coil thats reason for me wanting to try to get some pwm in sim. \$\endgroup\$
    – Eae
    Jan 26, 2015 at 9:07

2 Answers 2

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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.

enter image description here

enter image description here

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.

schematic

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  • \$\begingroup\$ There is a pro version for Every Circuit. Costs about $10 I bought into it. I don't think I would have come this far without it. \$\endgroup\$
    – Eae
    Jan 26, 2015 at 10:03
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I'm sorry, but I'm going to sound harsh.

It's not a matter of what you're doing wrong - I can't figure out what you're doing right.

Why are you feeding logic gates with a sine wave? You should be using a square wave with a low of 0 and a high of 5 volts. What technology are the gates? CMOS? TTL? What is the logic supply voltage?

Why do you have resistors in this circuit? What function are they supposed to serve?

Why do you expect the gate outputs to change? It looks as if the sine wave has too low an amplitude to cause the gates to change state, so you would expect the NOR output to stay high (both inputs are low), and the AND output to stay low (same reason). And that's exactly what's happening.

If the upper trace is the NOR gate output, it is not pulsing, although its amplitude is varying somewhat.

So I'm stumped. Please explain exactly why you think the circuit should work, and exactly what the circuit is supposed to do.

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  • \$\begingroup\$ My intent is to simulate PWM as close as to what the IR2104 puts out when it's Ho pin is driven high for 100 micros then LO for 100 micros and then a pause. \$\endgroup\$
    – Eae
    Jan 26, 2015 at 6:59
  • \$\begingroup\$ Yes I am aware there are some resistors in my circuit. It's a bit tough to connect them together without creating a short circuit. \$\endgroup\$
    – Eae
    Jan 26, 2015 at 7:00
  • \$\begingroup\$ My intent I think is clear in my original question. I'm looking for a PWM design based off of an Nor and and gate that will light both lamps. Yes I know it's probably looks bad. Hopefully I can learn from the experience. \$\endgroup\$
    – Eae
    Jan 26, 2015 at 7:02
  • \$\begingroup\$ Essentially I'm looking for a way to get PWM into my Every Circuit program since an IR2104 is not available. It was suggested to use this NOR and AND gate. I don't really understand about the wave not being high enough. I changed to square wave type of a pulse but that didn't change that fact that the lower lamp doesn't light up. \$\endgroup\$
    – Eae
    Jan 26, 2015 at 7:37
  • \$\begingroup\$ @user2209542 what he's saying is that that sine's amplitude does not go high enough for the logic gate to register it as a 'high'. \$\endgroup\$
    – efox29
    Jan 26, 2015 at 8:38

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