OK this isn't working like I expected :) Maybe you can help explain why?
From my understanding R3 and C2 set the frequency of the output from U5, U7 then inverts and creates a square wave of the same frequency.
R6 and C3 create the reference voltage that U6 uses to vary the duty cycle of the...
It seems to be a limitation of the LM324 spice model I downloaded from LTSpice (the model is from National). If I swap it out for a LT6231 that comes with LTSpice it runs fine.
dave
OK that is what I suspected. Sorry it's been a very long time since I've done spice :)
So I have it starting to run now but get the error:
Analysis: Time step too small; time =xxx, timestep = xxxe-15: trouble with 1n4002-instance d1. If I change the cap to make it simulate faster, it just has...
I'm trying to simulate a circuit that dims a 12V lamp over a 1.5hour time period. I use LTSpice as my simulator.
I need to do the simulation over about 7000 seconds. I set this with a max step size of 1s, but for some reason LTSpice thinks it needs a step size in the us range. It will take...
I have a nte1900 in my circuit hooked up as a current limit source. The connections are VI->30V, VO->31.5ohm resistor->VCCInt and Adj is connected to ground.
This should give me ~27V supply that is current limited to 40mA, at least that was my desire.
I've noticed that when VCCInt is open...
This circuit is just to model the alternating current seen in the legs of the dpdt relay. So I used an alternating current source to model that. Its not a voltage source.
Here is the entire circuit.
dave
It shouldn't matter. He also noted on the schematic that it was for use with a constant current source of 28mA.
Looking at your power supply, I don't think it does -30V to +30V, but 0V to 30V. You will need a little different circuit to get that to work. You'll need the use of a dpdt...
That is odd, when I click on the attachment it opens up across my entire screen. The images attached are about 1100x770 pixels.
I uploaded them to photobucket, maybe this will work better.
dave
As you can see I'm not afraid to talk to myself.
I had to dust off some 20 year old memories and remembered Kirchhoff is your friend. After looking at it that way, I figured I could easily fix this. If I have 40mA flowing through the current, and want to limit the forward bias current in...
The problem with this circuit is that all the current (40mA) will go through each LED and that may be too much for the diode. I don't think the current limiting resistor will do anything because the LM317 is going to do everything it can to drive 40mA, well unless I make the resistor so big...
Ok after thinking about this (and googling), I think it makes more sense to just put a 1N4148 in series with the LEDs. The spice sim looks good as well.
dave
All,
I'm using this 555 based polarity switching circuit as my base:
https://www.electronicspoint.com/555-timer-reverse-polarity-circuit-t250411.html
My supply is 30V DC so I'm using a DPDT relay to switch the legs. I'd like to put LEDs in the actual legs to show that everything is truly...