1N135 Optocoupler : Pspice Replacement

Thread Starter

lhern034

Joined Oct 23, 2017
46
upload_2018-1-6_21-42-34.png
here is what I added to the left side of the circuit.


the output seems to go to zero volts after a few milliseconds, initially the problem seems to be the open connection in 4N25 but I closed it it with a port and it started to simulate

I retried the original circuit but the Pspice does not seem to find the part
 

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Alec_t

Joined Sep 17, 2013
14,280
Your V7 pulse is much too short. Try ~19mS.
Incidentally, since this is only a simulation you might as well combine R4/5/6 into a single resistor. Likewise R8/9/10 and R11/12/13/15.
 

Thread Starter

lhern034

Joined Oct 23, 2017
46
do you mean by adding the capacitors?
In LT Spice:
what did you put as the diode properties?

How would I put a component like the one in the file?
 

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Thread Starter

lhern034

Joined Oct 23, 2017
46

Thread Starter

lhern034

Joined Oct 23, 2017
46
I don't understand what you are trying to do. The circuit is designed simply to generate negative-going pulses.
Hey Alec_t,

So basically, I recently found out that the load will need the pulses to oscillate the currents/voltages on the load in order for the entire system to work.
To do this it would be best to have an H-bridge implemented on the Load. The problem with this now, is that the H-bridge ICs work with positive pulses , due to them being more readily available with N-CH Mosfet. So I switched the circuit to give a positive pulse.

upload_2018-1-20_15-59-36.png

I changed the blue part of the circuit so that it gives a positive pulse, now I just need to know if there are any negative gate drivers that would amplify the input pulse to complete the circuit, so that I can find the proper H-bridge IC or Mosfets to make it work.


will a LM5110 do it? If so how would I connect it or get the LT schematic for it?
 
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Alec_t

Joined Sep 17, 2013
14,280
The LM5110 is not able to drive high-side N-channel MOSFETs easily. A driver with a bootstrap feature (e.g. IR2110) would normally be used for that.
I think that your present circuit, unfortunately, is unsuitable as the basis for driving a load with dual-polarity pulses. It only slowly charges a capacitor which is then discharged rapidly. It would probably be better to start from scratch with a new circuit designed to use an H-bridge.
What will be the repetition frequency of the dual-polarity pulses? Will the pulses alternate in polarity?
 

Thread Starter

lhern034

Joined Oct 23, 2017
46
It would probably be better to start from scratch with a new circuit designed to use an H-bridge.
What will be the repetition frequency of the dual-polarity pulses? Will the pulses alternate in polarity?
Yeah, we are going for something of at least/about 50Hz and it should alternate after every pulse. So after one positive current pulse, there would be a negative pulse and so on and so forth. the alternating pulses would also be controlled by the arduino.

So Arduino would control the input pulse and decide the polarity of pulses it outputs, with the H bridge design.

In post #71, the main MOSFET in blue is a PMOSfet
 
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Thread Starter

lhern034

Joined Oct 23, 2017
46
Understood, but for H-bridge use high-side NMOSFETs are often preferred because high voltage, high current, low Rds(on) types are more widely available.
Yes, this is why I needed to output a purely positive pulses and successfully did that by switching to a PMOS and reversing the voltage polarities.
This makes it easier to make the H-bridges that have NMOS work with the circuit.

I just need to make the red part to output -12V when the arduino wants to
 
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