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I have an astable multivibrator circuit that makes square waves at 40kHz ... at least in the simulator. I had to make it operate in a narrow voltage range to get the 2N2222 transistors to switch that fast. Maybe I can find faster transistors but for now, I'm going to try to narrow the pulse...
KISS,
The Velleman kit does not go to the 40kHz frequency, I'm aiming for (as per your suggestion which I 100% agree is required). It's limited to 5kHz. According to the data sheet, the SG3525 ic goes to 100kHz, which makes it worth consideration and I'll put some time into studying the...
MrAl,
The 5ms square wave shown is the best I can get from this circuit. I have not ahd a chance to try adding components to reduce the voltage. I've taken a step backwards to learn more about rc circuits.
Here is the square wave generator circuit I have come up with using an LM324/NS. It...
alec-t,
I found the potentiometer on the user group and put it into my circuit schematic. I'm still runnng through some trial and error exercises trying to get the frequency of a square wave generator up to 40kHz - double the upper limit of human hearing.
My approach is to try to reduce the...
Alec-t, Thanks for hanging in there with me. R5 and R6 comprise a 20k potentiometer. I could not find any symbol or Spice model for a variable resistor/pot.
Meanwhile I'm wading itno PWM starting with square wave generators. I have sucessfully simulated several circuits to produce square waves...
I'd still like to have a better understanding of how to utilize non-LT components. I'll be looking into that more as I work on the PWM part of this project.
It works ! In simulation anyway. This is what I have for now after working with LTspice. Probe the two outputs "PWM driver voltage" and "Hi-speed fan switch". R1 and R2 are my attempt at getting the two outputs somewhere near where I predict they will need to be.
I am beginning to get more of...
I'm nearing completion of the .asc file representing the circuit I have, so far. The circuit that seems to work with the other simulation software. I'm still bogged down in utilizing non-LT componenets. I found what to do to get the LM324 op-amp but am now grappling with the BC107 npn bjt. I'll...
GOOD NEWS !
Thanks MrAL and alec-t for pointing out how to plot graphs. I am finally getting something besides frustration after opening an .asc file with LTspice. I can now look at a square wave output after running a simulation with LT !!! Thanks to messages I read in the Yahoo user's group...
alec-t,
I am still not able to do much with LT Spice yet. I am attempting to learn how to copy library models from the Yahoo group so I can use them. In particular the LM324/NS opamp. Apparently, I am not the only one having trouble with this. Maybe I need to find suitable Linear Technology...
MrAl,
You are 100 % correct in assuming I am learning as I go. My electronics deign/building experience has so far been very limited. Years ago, I desigend and built a small adjustable power supply with a bunch of diodes/voltage multiplier, transformer and adjustable voltage regulator, a...
alec_t,
I will be putting in what I have learned are called "bypass capacitors". One for each opamp. If memory serves me correctly (my head is swimming in lots of new tidbits of information), they will be on the inputs to ground and each about 0.01mfd. I'm still not sure how/what they do...
Alec_t, I think I may have said it wrongly. Indeed there is quite a lot of discrepancy from one sender to the next. The quality of the parts that suppliers sell for these cars has always been a problem. I've learned to cope.
I've also plugged your circuit into the one I'm s-l-o-w-l-y getting a...
alec_t, According to one source, the resistance range of the temperature sending unti, for normal operating temperature, gauge reading at "N", in the centerpoint of the needle's sweep, is around 100 - 150 ohms. I'll know better once I take the sending unit out and take some warmup/cooldown...
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