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Old 30th May 2019, 5:45 am   #23
Chris55000
Nonode
 
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
Posts: 2,853
Default Re: Bell and Howell TQII 1652 16mm projector

Hi!

The 28V max needed for an LM2917–8 can be provided by an LM317T adjustable regulator or a 7824 with a 3.9V zener in parallel with a 10u 25V electrolytic in its middle ("GND") lead, or, if you can find space in your Projector, a small "LM317 Adjustable PSU Module", which you can buy cheaply online from Chinese supply sources, either ready–built or as a kit of parts with a bare pcb!

A darlington transistor such as the TIP147 or BDX53 should do for the LM2917–8 circuit example suggested in the previous post!

I wouldn't be at all surprised to find B & H have buried a '2917 in that module to begin with – it is, after all a similar speed control arrangement with simple switched potential dividers adjusted for each film speed!

Chris Williams
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Last edited by Chris55000; 30th May 2019 at 5:55 am.
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