Hey guys. I'm a CompE student so my electrical design knowledge regretfully doesn't extend far into SAFELY controlling high voltages. I have five 120V AC lightbulbs on a lamp and I need to control them individually with a computer. I've constructed the lamp, written the software, and built the computer interface, but can anyone recommend a way to safely control 120V with a 5V DC control line?
Or can you recommend a fairly inexpensive switch I can buy?
Relays? How much current are you talking about, are these standard bulbs (60-100W)? If you need it to be fairly small, then triacs may be the way to go.
What's wrong with a relay? D from BC
cmos -> transistor -> optoisolator (triac driver, zero crossing) ->
triac or alternistor
That's what I use. The key is layout - keep low voltage copper away from high voltage copper, use larger trace/space for high voltage, plan for insulating the high voltage section to protect the user.
Use an alternistor if you expect inductive loads.
snipped-for-privacy@purdue.edu wrote in news:1176337055.564500.83330 @w1g2000hsg.googlegroups.com:
A relay or a solid state relay. I think Radio Shack (cringe) might still sell one that can switch up to 3 amps at 125 VAC...
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Solid State Relay.
Don't have a "ground plane" going between the two areas.
Put the low voltage signals on a connector on one end of the PCB. Put the high voltage signals on a connector on the far end of the PCB.
Make sure to pick connectors that can't be partially or fully mated wrongly.
In other words assume an idiot is going to work on it. The idiot may even be you one sleepy morning or late night.
Go Purdue!
You need two things:
A relay made for 120 vac and about a 1KW CONTACTOR rating. P$B T92 seies for this.
An interface to go from the PIc I/o pin and to drive the Coil part of the T92 contatcor relay. We use this in the backend of a wireless prime power actuator switch. Link here..
Contact me for a breadbaord
Marc
On a sunny day (Thu, 12 Apr 2007 11:55:00 -0700) it happened LVMarc wrote in :
eh, From MOC3010 triac output optocoupler application note:
mc3020 and a triac, - google for 3020+datasheet
Bye. Jasen
Crydom solid state relays.
We used them in the 70s and I'll be damned they still make them and Digikey has them in stock.
They start at US$23 -- not sure if that satisfies your cost criterion.
Geno
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