Looking for simple Triac circuit

[ted weber]

Looking for a master/slave triac circuit to control a couple hundred watts,
where the triac circuitry senses the master load (device turned on), and then
it boots up the slave outlets. I thought I saw a really simple circuit several
years ago but now all I can find on the net are rather complex circuits with
several transistors, diodes, etc.

Thanks,

Ted

 

[martin griffith]

On Sat, 22 Oct 2005 20:31:41 GMT, in sci.electronics.design

Looking for a master/slave triac circuit to control a couple hundred watts,
where the triac circuitry senses the master load (device turned on), and then
it boots up the slave outlets. I thought I saw a really simple circuit several
years ago but now all I can find on the net are rather complex circuits with
several transistors, diodes, etc.

Thanks,

Ted

www.epanorama.net good starting point for loadsa stuff


martin

 

[Phil Allison]

"ted weber"

Looking for a master/slave triac circuit to control a couple hundred
watts,
where the triac circuitry senses the master load (device turned on), and
then
it boots up the slave outlets. I thought I saw a really simple circuit
several
years ago but now all I can find on the net are rather complex circuits
with
several transistors, diodes, etc.

** Those "really simple" circuits usually had a serious flaw.

When low current loads were used as the master, the triac was not reliably
triggered in both polarities resulting in a DC component reaching the other
loads - then the smoke got out.



........... Phil

 

[ted weber]

** Those "really simple" circuits usually had a serious flaw.

When low current loads were used as the master, the triac was not reliably
triggered in both polarities resulting in a DC component reaching the other
loads - then the smoke got out.

This application is specific, so the load will always be a couple hundred
watts on the master and the other loads.

Any idea where that simple circuit may be found on the net?


Ted

 

[Pooh Bear]

Looking for a master/slave triac circuit to control a couple hundred watts,
where the triac circuitry senses the master load (device turned on), and then
it boots up the slave outlets. I thought I saw a really simple circuit several
years ago but now all I can find on the net are rather complex circuits with
several transistors, diodes, etc.

You think that " several transistors, diodes, etc. " = complex ????

I suggest you re-think.

Esp for a master slave configuration.

Graham

 

[Ross Herbert]

Looking for a master/slave triac circuit to control a couple hundred watts,
where the triac circuitry senses the master load (device turned on), and then
it boots up the slave outlets. I thought I saw a really simple circuit several
years ago but now all I can find on the net are rather complex circuits with
several transistors, diodes, etc.

Thanks,

Ted

Try http://www.discovercircuits.com/Andy/Autopowerswitch.pdf

 

[Phil Allison]

"Ross Herbert"

Try http://www.discovercircuits.com/Andy/Autopowerswitch.pdf

** ROTFL !!!

That is EXACTLY the sort of schematic the OP was complaining about.

Chocka with complication !!!




........... Phil

 

[John Larkin]

Looking for a master/slave triac circuit to control a couple hundred watts,
where the triac circuitry senses the master load (device turned on), and then
it boots up the slave outlets. I thought I saw a really simple circuit several
years ago but now all I can find on the net are rather complex circuits with
several transistors, diodes, etc.

Thanks,

Ted

Just a current transformer over one leg of the master power line,
feeding the gate of a triac, said triac switching the slave.

John

 

[[email protected]]

Just a current transformer over one leg of the master power line,
feeding the gate of a triac, said triac switching the slave.

John

That's a good solution for resistive loads, but if the master is some
sort of partially inductive load with the current lagging the applied voltage,
then the slave may see a somewhat chopped version of the AC line voltage. At
least on the first half cycle. That may or may not be a problem.

The four-quadrant gate action may take care of keeping the triac turned
on for half-cycles after the first.

Jim

 

[Spehro Pefhany]

That's a good solution for resistive loads, but if the master is some
sort of partially inductive load with the current lagging the applied voltage,
then the slave may see a somewhat chopped version of the AC line voltage. At
least on the first half cycle. That may or may not be a problem.

The four-quadrant gate action may take care of keeping the triac turned
on for half-cycles after the first.

Jim

Maybe unlikely, depending on the nature of the loads, but I'd be a bit
worried about possible asymmetrical triggering, leading to DC in the
winding of a transformer or motor which might be in the switched load,
and thus copious amounts of smoke pouring out and that sort of
embarassing outcome.


Best regards,
Spehro Pefhany

 

[John Larkin]

That's a good solution for resistive loads, but if the master is some
sort of partially inductive load with the current lagging the applied voltage,
then the slave may see a somewhat chopped version of the AC line voltage. At
least on the first half cycle. That may or may not be a problem.

The four-quadrant gate action may take care of keeping the triac turned
on for half-cycles after the first.

Jim

There are always unstated details, it seems.

Well then, you could rectify and filter the gate drive, or have the ct
drive a small rectifier/filter into a power ssr.

John

 

[DaveM]

Looking for a master/slave triac circuit to control a couple hundred
watts,
where the triac circuitry senses the master load (device turned on), and
then
it boots up the slave outlets. I thought I saw a really simple circuit
several
years ago but now all I can find on the net are rather complex circuits
with
several transistors, diodes, etc.

Thanks,

Ted

You might be thinking of a circuit like the one at
http://ourworld.compuserve.com/homepages/Bill_Bowden/page8.htm#aclatch.gif
It's not very complicated, as power control circuits go.
If you absolutely want a triac to control the slave loads, just replace the
relay with am optoisolator and triac combination. You can also replace the
homemade current sensor with a real current transformer that will be more
predictable.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in
the address)

Never take a laxative and a sleeping pill at the same time!!

 

[ehsjr]

Looking for a master/slave triac circuit to control a couple hundred watts,
where the triac circuitry senses the master load (device turned on), and then
it boots up the slave outlets. I thought I saw a really simple circuit several
years ago but now all I can find on the net are rather complex circuits with
several transistors, diodes, etc.

Thanks,

Ted

Look for "Jim Thompson Inspired Switch" in the abse newsgroup.
I'll be posting it today.

Ed

 

[ted weber]

Look for "Jim Thompson Inspired Switch" in the abse newsgroup.

I'll be posting it today.

Ed

Thanks very much. Where is abse?

Ted

 

[Fred Bloggs]

Thanks very much. Where is abse?

Ted

I posted this a while back, put a MOV across the L and N where they
enter your little *plastic* box containing the parts. It uses the Radio
Shack 10A relay (1200VA load). If your master load causes triggering
problems then you may have add a line rated 0.1U capacitor between its
switched line and neutral.
View in a fixed-width font such as Courier.

..
..
..
.. RS relay 275-217
..
.. .-------------------o----v
.. | o-------+-----.
.. | | |
.. | 1A ------ | |
.. | 400V .-|\ \ \ |-. | |
.. | TRIAC | ------ | | |
.. +-----|<|---------' | | |
.. | |>| | | |
.. | | | | |
.. | | | | |
.. | | | | |
.. | | 22 | | |
.. | '--/\/\----. | | |
.. | 1/4W | | | -|-- N
.. | | | | | - | E
.. | | | | | o| O
.. | 4x 1N4001 | | | |--- | N
.. | | | | -|--
.. ___ +---|>|--|>|------+ | | |
.. | \ | | | | |
.. L ---| |--+---|<|--|<|------+ | | |
.. | | | | | |
.. N ---| |--+-----------------|----------|---|-----'
.. ---/ | | | |
.. | | | |
.. GND---. | -------- | | | --------
.. | | | | | | | | |
.. | | | __ | | | | | __ |
.. | | | |------' | '-----| | |
.. | | | -- | | | -- |
.. | | | ____ | | | ____ |
.. | +------| |----------------' .----| | |
.. | | | ---- | | | ---- |
.. '---------------O-------------------------------O |
.. | | | | | |
.. | -------- | --------
.. | MASTER | SLAVE
.. | |
.. | |
.. '--------------------------------'
..

 

[Rich, Under the Affluence]

Thanks very much. Where is abse?

It's the newsgroup, .
You need a real news server at your ISP (or I guess there are
news servers for hire out there these days). I notice you're
not a google poster, so you probably have it unless your
local sysop is censoring you. ;-)

Good Luck!
Rich