Op-Amps, PWM and Ignition Coils Tutorial - Page 1
Forum section: electronics / projects

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 21, 2011, 06:12:12 pm
content: A new video (with a quiz!) has been posted on The Signal Path:In this episode 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.Please visit:http://www.TheSignalpath.com

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 21, 2011, 07:19:51 pm
content: Also please feel free to leave the answer to the quiz here.

author: Unknown
author_rank: Unknown
timestamp: August 21, 2011, 07:27:54 pm
content: Another great episode. Thank you guys.on a side note it is maybe a tad didactic, which is totally fine by me, but may loose some views from a broader audience

author: armandas
author_rank: Frequent Contributor
timestamp: August 21, 2011, 08:31:33 pm
content: Your sound quality is a bit on the low side. Not sure what it is, could be clipping or something. Other than that, good videos.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 21, 2011, 08:36:06 pm
content: Thanks, I will look into that. I am not happy with our video conversion tools at the moment. If someone has ideas with regards to that, please let us know.

author: Simon
author_rank: Unknown
timestamp: August 21, 2011, 08:51:54 pm
content: Very interesting, sound was fine for me but was totally lost when the spark came on but i guess that was due to auto volume settings and the amount of noise the spark made

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 21, 2011, 11:02:22 pm
content: Yes, the spark messed up everything, including the scope!

author: Kozmyk
author_rank: Regular Contributor
timestamp: August 22, 2011, 12:04:35 am
content: I'd have been interested to see the scope trace at a slower sweep rate when the spark was drawing.There appeared to be a lower frequency modulation going on.Videos were a good mix of theory and practise I thought.Shame about the sound phasing/decoding problems.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 22, 2011, 03:45:14 pm
content: The scope just goes crazy when the sparks appear. There must be tons of harmonics within the transformer and since it is not unilateral at all, a lot of it must jump back into the Darlington pair and messes up the scope. And lets not forget about all the EM radiation fro the 30kV sparks...We will try to fix the sound quality and video quality for our future episodes.

author: nzo
author_rank: Regular Contributor
timestamp: August 27, 2011, 02:00:19 am
content: Those sparks transmit on the whole RF frequency spectrum at once. Your whole lab would have been turned into a broad spectrum receiverHave you triedSorenson Squeezeto process your vids?

author: Wartex
author_rank: Frequent Contributor
timestamp: August 27, 2011, 05:56:34 pm
content: Quote from: Hugoneus on August 21, 2011, 06:12:12 pmDo you refer to yourself in 3rd person?On a serious note, your videos are very high quality material. Ever since Dave was laid off the eev vids declined in quality big time. I feel like watching evening news discussing a random industry now.