photogate scr trigger

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Joeshmoe

Joined Jan 12, 2007
66
i hooked up the trigger output to the scr im not sure what kind of schem you want i would like to give you any information you need to help me thanx
 

thingmaker3

Joined May 16, 2005
5,084
Here's the schematic. I can't for the life of me figure out how this is supposed to work. The load has one side connected to ground and the other side connects through the SCR to ground.:confused:
 

Ron H

Joined Apr 14, 2005
7,014
This will trigger when the light from the LED is blocked. If you need it to trigger when the the light is not blocked, swap the position of the phototransistor with the 100k/1k series resistor combination.
 

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Thread Starter

Joeshmoe

Joined Jan 12, 2007
66
thanx for the schem but it doesn't seem to work... it it is possible that i am not wiring it properly i havent been working with schems like this for that long i am getting inconsistent readings and its just not triggering it
 

Thread Starter

Joeshmoe

Joined Jan 12, 2007
66
I did hook it up that way and it didnt work.. i think the problem is that the voltage difference is not large enough (between blocked and not blocked).trigger does have a 9v battery.
 

thingmaker3

Joined May 16, 2005
5,084
The trigger circuit has a 9v source, but what about the load? What about the thing that gets triggered? Looks to me like it has both sides connected to ground.:(
 

Thread Starter

Joeshmoe

Joined Jan 12, 2007
66
i think the problem is that the voltage isnt raising high enough...when the beam is uninterrupted it is at about .3 volts and when interrupted it is about .45 volts
 

Ron H

Joined Apr 14, 2005
7,014
i think the problem is that the voltage isnt raising high enough...when the beam is uninterrupted it is at about .3 volts and when interrupted it is about .45 volts
If you're talking about the gate voltage, you may have too much ambient light on the phototransistor, or you need to adjust the pot, or both.
 
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