Moderators: Dave Moll, Andrew Davie, Steve Anderson
Steve Anderson wrote:
Postscript: What's R905 for? Any guesses? It's not an easy nor obvious answer! Remember, the CRT grid should not go positive so there's no current in R905, therefore no voltage drop across it. So why is it there? Hint: and a rather obscure one...R905 should be mounted right on the CRT socket pin, really close to the CRT, preferably within 1cm, I should have mentioned this before, but it 'slipped through the cracks'.
Steve Anderson wrote:
The rather odd thing here is we're using a PNP transistor with an NPN photodiode, they're usually of the same polarity (with valves/tubes they have to be). But there's no base connection in the phototransistor so as long as it conducts current, the tranny will respond and doesn't care.
Steve A.
Steve Anderson wrote:Thanks Harry, just post the static photos that are pertinent subject matter, that's all that's needed.
"Simplicity is the elegance of design", which includes getting your message across here..
Steve A.
Steve Anderson wrote:OK Harry, that's enough. Now follow up this as to how you intend to use it...remember no bright (daylight) exposure whilst energised....
Steve A.
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