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Making a high speed pulser

RobertB50

Sep 16, 2016
5
Joined
Sep 16, 2016
Messages
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Hi, all.
I need to pulse each sensor in a stack of of roughly 1500 sensors. There has to be about 20 microseconds in between pulses, or else my 100khz counter will lose tract. I tried using a LDR that fired a LED... which in turn fired the next LDR and so on. With a small cap in each branch I got this method to work, but LDRs fire way TOO SLOW. Using this method would take 75 seconds to count up all the sensor inputs. I ONLY have 1 second to do this scan. I am COUNTING inputs, NOT timing the whole scan.
I want to try replacing the LDRs with photodiodes in the above circuit. But I am afraid they are TOO fast for my counter to keep tract of. I am not going to go the 555 timer route. I would have to solder in 166 of them.
Any help would be greatly appreciated.
 
Last edited by a moderator:

davenn

Moderator
Sep 5, 2009
14,254
Joined
Sep 5, 2009
Messages
14,254
Hi, all.
I need to pulse each sensor in a stack of of roughly 1500 sensors. There has to be about 20 microseconds in between pulses, or else my 100khz counter will lose tract. I tried using a LDR that fired a LED... which in turn fired the next LDR and so on. With a small cap in each branch I got this method to work, but LDRs fire way TOO SLOW. Using this method would take 75 seconds to count up all the sensor inputs. I ONLY have 1 second to do this scan. I am COUNTING inputs, NOT timing the whole scan.
I want to try replacing the LDRs with photodiodes in the above circuit. But I am afraid they are TOO fast for my counter to keep tract of. I am not going to go the 555 timer route. I would have to solder in 166 of them.
Any help would be greatly appreciated.


Everyone
Before you respond, have a read of this thread

https://www.electronicspoint.com/threads/help-connecting-555-timer.280492/#post-1706662

that I closed some time ago when not enough clear info was supplied and the thread got out of hand with wild guesses
because @RobertB50 didn't return to supply better info


The moderators will monitor this thread to make sure it doesn't go the same way
@RobertB50 please supply some drawing of how you expect this to be connected up etc


Dave
 

BobK

Jan 5, 2010
7,682
Joined
Jan 5, 2010
Messages
7,682
Have you thought about a schmitt trigger, resistor and capacitor for each delay unit?

Bob
 

BobK

Jan 5, 2010
7,682
Joined
Jan 5, 2010
Messages
7,682
Or, just to tweak a couple of forum mrmbers, how about a chain of 1500
555s?

Bob
 
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