Poor explanation... or is it me? - Page 1
Forum section: electronics / general

author: eti
author_rank: Super Contributor
timestamp: December 11, 2022, 06:23:56 am
content: Is it me, or is the theory of operation of this camera flash circuit, worded poorly?http://www.increa.com/reverse/dc/index.htm

author: IanB
author_rank: Super Contributor
timestamp: December 11, 2022, 06:50:26 am
content: Quote from: eti on December 11, 2022, 06:23:56 amI think the explanation is laid out logically. Following it is easier if you have a print out and mark various parts with a pencil as you go along.It does slightly skip over the reset part of the charging oscillator, but if you have followed the previous steps you can fill in the gaps.

author: eti
author_rank: Super Contributor
timestamp: December 11, 2022, 07:17:36 am
content: Thanks. So much.

author: Brumby
author_rank: Unknown
timestamp: December 11, 2022, 11:51:09 pm
content: That reminds me ... I still have a couple of hundred boards I recovered from such cameras some time ago. I remember approaching film processing establishments (now long gone) and asking them to hang on to the carcasses for me. Some refused (because others had requested things be saved, then never came back to collect them) but some were agreeable. I made sure I returned regularly to collect the booty - with an enthusiastic Thank You - and to let them know when I was done.The recovered AA batteries still had an appreciable amount of energy in them. Even after giving some away, I didn't have to buy any for a couple of years.

author: IanB
author_rank: Super Contributor
timestamp: December 12, 2022, 12:04:46 am
content: Quote from: Brumby on December 11, 2022, 11:51:09 pmEach one charges the flash capacitor to about 300 V.So if you were to put 100 of them in series you could get about 30 kV with close to 1 kJ of energy behind itThat would be enough to make the most enormous bang--not to mention being incredibly dangerous

author: David Hess
author_rank: Super Contributor
timestamp: December 12, 2022, 07:32:03 am
content: Quote from: eti on December 11, 2022, 06:23:56 amI am not surprised. Blocking oscillators are weird.Quote from: IanB on December 12, 2022, 12:04:46 amI know first hand that high voltage DC sources should use as little capacitance as possible for safety.

author: eti
author_rank: Super Contributor
timestamp: December 12, 2022, 08:16:25 am
content: I once connected a few boxes full of PP3 9V batteries together in series, clip to clip, and then grabbed a wire and made a nice searing arc. I'm pretty sure I was aware of the danger, but oh boy was it fun! I think it was about 100 of them.

author: dmills
author_rank: Super Contributor
timestamp: December 12, 2022, 12:27:04 pm
content: High school design and technology, (Now I think called 'resistant materials?), I was allowed to build a guitar amp but it had to be battery powered.Mine was, a pair of EL34s, lead acid cyclons for the heaters and 60 PP3 in series for the plate. They were nicads and I learned a lot about fusing HVDC on that project.We will gloss over the charging harness (1200V bridge off the mains with a series resistor) for the B battery.

author: Brumby
author_rank: Unknown
timestamp: December 13, 2022, 11:52:05 am
content: Quote from: IanB on December 12, 2022, 12:04:46 amYouris quite the understatement. It needs to be an order of magnitude or two larger.

author: Brumby
author_rank: Unknown
timestamp: December 13, 2022, 12:22:59 pm
content: .... though Idohave a 30kV voltmeter.

author: David Hess
author_rank: Super Contributor
timestamp: December 14, 2022, 12:08:05 am
content: I think the biggest capacitor bank I have worked with was the plate glass capacitor on my big tesla coil. It was about 0.1 microfarads and 20 kilovolts so only 4 joules, but it sure was loud when it shorted out.

author: IanB
author_rank: Super Contributor
timestamp: December 14, 2022, 12:46:05 am
content: Quote from: David Hess on December 14, 2022, 12:08:05 amUsing E = ½CV² I think that would be 20 J, so no wonder the bang?