solid state dimmer

I'm looking for a solid state relay that I can use basically as a dimmer. I
have a circuit board hooked up to an AMD 186 evaluation board that I am
using to do temperature control. I'd like to control the vac 120 output by
varying vcd input (ideally 0-5 vcd as my power supply is 5 vcd -- of course
I could add another power supply and voltage regulator if need be).

I'm not quite sure what the industry terminology for such a relay is.
"Solid state dimmer" doesn't find me exactly what I'm looking for. Is there
an attribute for relays that I should use in my on-line search?

Thanks

 

Are you referring to a Silicon Controlled
Rectifier or a Triac, or are you looking
for something else?

A quick search on 'triac dimmer opto
schematic' brought up this, for example:

http://www.commlinx.com.au/schematics.htm

HTH

 

I'm not familiar with these terms. Basically I want a solid state relay
that I can control the vcd output by varying the vcd input. I'm currently
using several solid state "hocky puck" style relays to turn things on and
off but there are some devices that I would like to "dim" instead.

 

Oops I meant "vac" output...

 

If you're talking 120Vac, you don't control
"vcd output", if I understand what you mean
by the term.

If you're looking for something to provide a
0-120Vac sine wave output, you want either a
variable autotransformer or something equally
expensive.

Your 'hockey puck' relays are probably opto-
isolated SCR's or Triacs; check your specs.

You can set an SCR or Triac to switch on for
only part of each AC cycle; how much of each
cycle is used determines the 'brightness' of
the output.

The website I listed has several 120Vac
dimmer circuits. They should give you some
ideas.

 

Subject: Re: solid state dimmer

Mr. Fields is correct. If you Google the phrase, eventually you'll come up
with the Velleman K8003 kit, which optoisolates an input DC voltage, and uses
that to control an AC load up to 750 watts (resistive, heater and lamp loads
work best here.) It's about $25 USD per I/O poinit, and should do what you
want (it is a kit, so you'll have to put it together yourself).

One small issue you might have here is that the kit triac won't turn on at all
until you've got the Vf of the opto LED covered (about 1.5VDC or so). If
you've got a -5VDC supply for your EVB, it might help to externally convert the
voltage into a current to feed the LED. Something like this would be
relatively easy, and you could make 4 with one LM324 quad op amp (view in fixed
font or M$ Notepad):

K8003 Dimmer Kit Mod.
Jumper out
series resistor
+
.-----------o------o - - - - o----o---.
| | |
| K8003 DC Dimmer Kit - V ~
| ^ - ~
| - | |
| .--o---------------------o---'
220 ohm | +5V |
___ | |\| |
o--|___|-o--|-\ |
0-5VDC In | >--'
.---|+/
| |/|
| -5V
===
GND


created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de
If this isn't good enough, you may want to run a calibration curve, then have
a lookup table (use a true RMS AC meter for this).

http://www.velleman.be/Downloads/0/Manual_K8003.pdf

Good luck
Chris

 

Thanks guys. I'll look into this. Knowing the terminology will help
greatly.

So can I assume that there are no variable output relays out there as I
described? It seems like there would be quite a market for such a thing.