Troubleshooting a digital thermostat
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From: Geo on 2 Feb 2010 10:20 On Tue, 02 Feb 2010 14:54:02 +0000 (GMT), "Dave Plowman (News)" <dave(a)davenoise.co.uk> wrote: >In article <lvbgm5l9qavb1v2gjkck2sj2m945a5udel(a)4ax.com>, > Geo <hw9j-s5hw(a)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
From: Dave Plowman (News) on 2 Feb 2010 11:26
In article <m0ggm51t332jk1bea0ejare28lnl1fpoqp(a)4ax.com>, Geo <hw9j-s5hw(a)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(a)davenoise.co.uk London SW To e-mail, change noise into sound. |