circuit problems

[spondootre]

I've copied this circuit and I thought it was supposed to latch on with one press of the switch and off with another. However what I get running it at 12 volts is an output of 12v, then when the sw. is released it instantly drops to 0, if the switch is held on it drops to 0 after a few seconds indicating that the timer part is working fine. Any ideas?? Or is it supposed to do this?!

**broken link removed**

 

[audioguru]

I wish you attached a clear GIF or PNG file type here, instead of a fuzzy JPG file type over there.

I changed your circuit a little and I think it will do what you want. I have a much simpler circuit.

 

[spondootre]

Hi,

Thanks for the reply, i've updated the image to one a little clearer. I've just tried that mod and it's no better i'm afraid.
The simpler version wouldn't have the timer aspect though would it?

 

[audioguru]

I goofed on the mod. This one should toggle.
My simple circuit is the same as this mod. The output toggles each time the button is pushed but my simple circuit starts in a random mode when power is applied.

 

[hawk2eye]

I've copied this circuit and I thought it was supposed to latch on with one press of the switch and off with another. However what I get running it at 12 volts is an output of 12v, then when the sw. is released it instantly drops to 0, if the switch is held on it drops to 0 after a few seconds indicating that the timer part is working fine. Any ideas?? Or is it supposed to do this?!
.....................................................................................
The circuit should operate as a timer for 22sec as designed


BUT from your description:
< the sw. is released it instantly drops to 0, if the switch is held on it drops to 0
< after a few seconds indicating that the timer part is working fine when the switch is held ON

If your description is accurate the circuit is NOT “working fine” when Q2 =1 operates for "a few seconds"
("few seconds" to me is 3 to 5 seconds)
22M*1uf should hold the output Q2 =1 for a long time constant of 22 sec

Gross mistakes that might cause the time to reduce 22 sec to “ a few seconds”
for example:
some kind of a high resistance parallel path between the Q2 and 0.1uf
- A bad, leaky diode ?
- 2.2 Megohm or 0.01uf instead of 22 Megohm, 0.1uf

CHECK:
add 22 Megohm in parallel to the existing 22Megohm
does the measured time delay become reduce by 1/ 2 ?

add 0.1uf in parallel to the existing 0.1uf s
does the measured time dealy increase by a factor of 2 ?

I would be interested in the results of such tests.

hawk2eye