Troubleshooting a digital thermostat

[Geo]

On Tue, 02 Feb 2010 14:54:02 +0000 (GMT), "Dave Plowman (News)"
<dave@davenoise.co.uk> wrote:

In article <lvbgm5l9qavb1v2gjkck2sj2m945a5udel@4ax.com>,
Geo <hw9j-s5hw@dea.spamcon.org> wrote:
Sounds a bit like my Danfoss TP75. It uses an Omron latching relay type
G6CK-2117P which works off a 20mS 3V pulse:-
http://www.omron.com/ecb/products/pry/121/g6c_2.html

Interesting - but nothing like those on my board. I no longer have it so
can't take pics. The description isn't that clear - does it take (near)
zero current when made or just a reduced amount? For long battery life it
would need to be zero. Nor did the noise it made when the 'switch'
operated sound anything like a relay.

No current at all. Imagine a balanced metal arm pivoted in centre and a coil at
each end with some remanent magnetism. A current pulse through either coil is
sufficient to overcome the small static magnetic pull and trip the bistable to
the other condition. The Danfoss WP75H uses a much larger Gruner 703H to switch
up to 25A for an immersion heater.

This article has a short explanation and some driving circuits:-
<http://www.electronicsweekly.com/Articles/2008/11/21/44977/circuits-drive-single-coil-latching-relays.htm>

--
Geo

 

[Dave Plowman (News)]

In article <lvbgm5l9qavb1v2gjkck2sj2m945a5udel@4ax.com>,
Geo <hw9j-s5hw@dea.spamcon.org> wrote:

The programmable thermostat I retro-fitted to the old system - allowed you
to set different temperatures for parts of the day and days of the week -
used four AAs for everything - no power from the line - and they lasted
about 2 years. They are a very worthwhile addition to an older system.

Sounds a bit like my Danfoss TP75. It uses an Omron latching relay type
G6CK-2117P which works off a 20mS 3V pulse:-
http://www.omron.com/ecb/products/pry/121/g6c_2.html

Interesting - but nothing like those on my board. I no longer have it so
can't take pics. The description isn't that clear - does it take (near)
zero current when made or just a reduced amount? For long battery life it
would need to be zero. Nor did the noise it made when the 'switch'
operated sound anything like a relay.

--
*I don't suffer from insanity, I enjoy every minute of it *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[Dave Plowman (News)]

In article <m0ggm51t332jk1bea0ejare28lnl1fpoqp@4ax.com>,
Geo <hw9j-s5hw@dea.spamcon.org> wrote:

Interesting - but nothing like those on my board. I no longer have it
so can't take pics. The description isn't that clear - does it take
(near) zero current when made or just a reduced amount? For long
battery life it would need to be zero. Nor did the noise it made when
the 'switch' operated sound anything like a relay.

No current at all. Imagine a balanced metal arm pivoted in centre and a
coil at each end with some remanent magnetism. A current pulse through
either coil is sufficient to overcome the small static magnetic pull and
trip the bistable to the other condition. The Danfoss WP75H uses a much
larger Gruner 703H to switch up to 25A for an immersion heater.

This article has a short explanation and some driving circuits:-
http://www.electronicsweekly.com/Articles/2008/11/21/44977/circuits-drive-single-coil-latching-relays.htm

Excellent - thanks for that. I can think of a few uses I could put them to.

--
*Why don't you ever see the headline "Psychic Wins Lottery"?

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.