J
James Arthur
Guest
bw wrote:
on the output transistor, but I screwed up--the output's
inverted, I used 'R3' twice, and I left out the diode
across R2.
I'll try to redeem myself.
+12v
-+-
|
.-------------------+----------+
| | |
[R1] [R3] |
| | |<'
| +--[R4]--| Q2
| D2 | |\ PNP
+--|>|---. | .-----+
| | Q1 | | | |> |
+--[R2]--+-----. |--' [D1] [relay] | |
| | | |<-. | | O O
O C1 --- | |--+----+-----'
\ --- |
\ | [R5]
O | |
| === ===
=== GND GND
GND
You don't need a gate protection zener for V+ <20v,
but that's a good idea for when it is.
Cheers,
James Arthur
I prefer the version with hysteresis for being easier"James Arthur" <bogusabdsqy@verizon.net> wrote in message
news:CjCpl.1746$Ez6.582@nwrddc02.gnilink.net...
I posted a couple circuits. Here's the fewest parts I
can manage:
+12v
-+-
|
.-----------------------+
| |
[R1] |
| D1 | |> /
+---|>|------. [relay] | /
| | | O O
| | |
+-----[R2]---+-----. |--'
| | | |<-. Q1
O C1 --- | |--+
\ --- |
\ | ===
O === GND
| GND
===
GND
If R2 = 1000 x R1, and the hold-ON is 3 minutes,
the turn-on time is <180mS.
James Arthur
There are many variations of this delay circuit. For someone testing this
R1=10k
R2=100k
C=100 uF
Should give around 10 second delay. Increase R2 for longer times.
Also, I'd add a 10 volt zener to the Gate of the MOSFET. This makes the
timing easier to modify and allows adapting the circuit for higher supply
voltages by protecting the gate.
on the output transistor, but I screwed up--the output's
inverted, I used 'R3' twice, and I left out the diode
across R2.
I'll try to redeem myself.
+12v
-+-
|
.-------------------+----------+
| | |
[R1] [R3] |
| | |<'
| +--[R4]--| Q2
| D2 | |\ PNP
+--|>|---. | .-----+
| | Q1 | | | |> |
+--[R2]--+-----. |--' [D1] [relay] | |
| | | |<-. | | O O
O C1 --- | |--+----+-----'
\ --- |
\ | [R5]
O | |
| === ===
=== GND GND
GND
You don't need a gate protection zener for V+ <20v,
but that's a good idea for when it is.
Cheers,
James Arthur