R
Robert Baer
- Jan 1, 1970
- 0
Didn't you know that mercury has been and is illegal?Spehro said:Nonsense, they're off-the-shelf.
http://www.newark.com/durakool/cfc2...ALL&mckv=kMV575ew|pcrid|dynamictrackcampaigns
Didn't you know that mercury has been and is illegal?Spehro said:Nonsense, they're off-the-shelf.
http://www.newark.com/durakool/cfc2...ALL&mckv=kMV575ew|pcrid|dynamictrackcampaigns
Didn't you know that mercury has been and is illegal?
They outlawed a naturally-occurring element? Sounds like something a
politician might do.
They outlawed a naturally-occurring element? Sounds like something a
politician might do.
Yes this is a one off. I'm building a custom thermostat to replace my wall thermostat. I know these furnace control circuits are 24VAC...
I did look at SSRs, but I'm leery about those because when they fail, they often fail closed.
The 3V limitation is actually a preference because the microcontroller used is 3.3V. I could have another regulator to provide relay coil power, but thought it might be nice to have one regulator.
^^^^^^^^The failures are unlikely,
but you can work around them by using a fuse and having
a second switch (needn't be an SSR) which is normally OPEN when the SSR is closed.
The second switch, when the SSR is commanded OPEN, gets commanded CLOSED
and blows the fuse. This kind of thing is common in interlocks (microwave oven door
switches, for example).
Relays don't require regulated power. You can use a single transistor to switch the coil
current, and just drive the transistor's base from the logic (with suitable current-limiting).
And turn all the wheels of all the cars hexagonal.
And turn all the wheels of all the cars hexagonal.
Cheers
Phil Hobbs
Well, what do you expect from the EC?Spehro said:They outlawed a naturally-occurring element? Sounds like something a
politician might do.
Best regards,
Spehro Pefhany
Didn't you know that mercury has been and is illegal?
Don't over-complicate this. Just use a mechanical relay! Dirt simple
and stone cold reliable.
Every electronic thermostat whose circuit I've analyzed uses bistable
relays.