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Timer circuit

P

P.Webb

Jan 1, 1970
0
Hi All,
I want to make a time delay circuit using transistors,
12v supply switch on a 3Watt bulb and go off after about 3 seconds
if possible, I don't want to use a relay or 555
and I would like to use pnp ZTX 751 transistors which I have plenty of !
Thanks.....Peter
 
J

Jonathan Kirwan

Jan 1, 1970
0
I want to make a time delay circuit using transistors,
12v supply switch on a 3Watt bulb and go off after about 3 seconds
if possible, I don't want to use a relay or 555
and I would like to use pnp ZTX 751 transistors which I have plenty of !

Peter, since I recently posted something close to what you want, I'd
like to save time and suggest that you might try something like the
following:
: +12V +12V +12V +12V
: | | | |
: | | | | Momentary
: | \ | | Pushbutton
: | / R1 | O S1
: | \ 33k | \
: | / | \
: | | | \
: D2 | | | O
: 1N4148 _|_ | |<e Q1 |
: /_\ +--------| ZTX751 |
: | | |\c PNP |
: | | | |
: | \ | |
: | / R2 +----------------+
: | \ 3.3k | |
: | / --- C1 |
: | | --- 0.47uF \
: | | | / 3W
: | | | \ LAMP
: | | | /
: +---------------+ |
: | | +------, |
: | | | | D1 |
: | | | | 1N4148 |
: | ||' M1 \ _|_ |
: | ||< BSS145 / /_\ |
: '--'|, \ | |
: | R3 / | |
: | 4.7M | | |
: | | | |
: gnd gnd gnd gnd

I haven't looked at the data sheet for the Zetex part, though. I'm
assuming that you already know it can handle the 3W load.

Jon
 
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