Op-Amps, PWM and Ignition Coils Tutorial (Part 3/3)

In this episode (Part 3/3) Shahriar discusses methods for generating a pulse-width-modulated (PWM) signal entirely in the analog domain by employing operational-amplifiers (Op-Amps). A total of four op-amps from a single power supply are used in unity-gain negative feedback, astable positive feedback, integrator and open-loop comparator configurations. The theory of operation as well as measurement are also presented. This episode also includes a quiz. Please post your answers in the comment section.

As a final experiment, an ignition coil is used to generate in excess of 20k volts! The combination of the PWM circuit and the ignition coil provides a stand-alone fully analog high voltage power supply.

Category:

Science & Technology

Tags:

• operational amplifier
• op-amp
• pulse width modulation
• PWM
• ignition coil
• integrator
• comparator
• negative feedback
• positive feedback
• square wave generator
• triangular wave generator
• high voltage
• spark generator

[lebeyes]

@4:44 The TIP147 is PNP, not NPN.

[TheSignalPathBlog]

@lebeyes Yes! Thank you. The schematic is correct which shows a PNP device.

[Jiraya12345]

These videos are fantastic, thank you so much!

And as I recall, it takes about 50,000V to create an inch long spark, so I suppose that would be about 20,000V per cm? I can't remember exactly, but I think that's about right.

[TheSignalPathBlog]

@Jiraya12345 Yeah, I think it is about 3kV per millimeter.

[Atlascol]

Great video!. But i've got a question, isn't necessary a diode for the transformer?

[TheSignalPathBlog]

@Atlascol Are you referring at the input or the output of the transformer? Also, the TIP147 Darlington device that I am using, has a built in clamping diode in it. I did not show this on the schematic.

[MrMac5150]

GOOD VIDEO

[maguyver1969]

If it is a standard coil like the one in your video and with the gap at .45 the voltage is gona be 15-30,000

[evhgl87]

I would love for you to apply higher mathematical theory in relation to circuit design. Very few people have the theoretical knowledge to be able to further explain outside of simple terminology what is actually going on - current undergrad

[Khwartz]

You're just perfect teacher! :) :-bd

[mlhvdmeij]

I don't think a clamping diode in the darlington will do anything in this circuit. Also, the secundary voltage is entirely defined by di/dt in the secondary winding and has nothing to do anymore with the primary winding. I agree with Atlascol that there should actually be a diode in the secondary winding to ensure no current can flow through the secondary winding while the transformer is in it's charging cycle.

[stivep1]

It is not AWG generator but amplifier operated by AWG.10KHz-1MHz 1-10V

I will give you some hints:

SG interface parts::LM393(both comparators used),1N4198 (2 pieces)1N4198 (2),21n60(2), transformer with primary winding with center lead. 4 secondary winding ( the same-equal)

H-bridge driver:starts after primary: 7N80(4), 1 special transformer 1:10 ratio,permeability 2000 (primary is spread equally) secondary is spread equally) 500V, 2A For you it should be 1 day of thinking.

Wesley

[stivep1]

by the voltage range 0-20 000V up to 1 Mhz no distortion to its extend of maximum of possibility

I have on bench 10kHz to 1 MHz 0-10 000V AWG right now that I'm in process of assembly and testing

I wish you the best.

You may become a genius or you may waste your time working for some lab or some employer It is up to you young man....All you need is motivation....

Wesley

[stivep1]

30 000V per centimeter

You did not show waveform at the output, at the spark gap and spectral components on spectrum analyzer, The video series is extremely educational . You suppose to be a teacher.

That is the best job for you. Another suggestion for project: HOW WOULD YOU BUILD AWG

FOR 2000-2000V? 0-1MHz Basics are good but your brain power needs excessive motivation to the area that is going to sparkle your true potential.

Wesley

PS: Science is my state of conciseness and my devotion.

[stivep1]

good job. Thank you. I'm in similar scientific field but directed to Overunity.

Is it possible? I have seen it in my own eyes. I have hold in my own hands device that was delivering power for 30 minutes activated by one single 1 second impulse and than at no external power supply or any power supply at all , working by itself.

Wesley

[maynardr6]

I appreciate you taking the time to refine your presentations. You're doing a great job.  I'm just learning, but I may end up doing this as a career one day.