On 4/15/2014 12:09 PM, David Cole wrote:
It is even stated as being RFI noisy... I wonder if it is Part 15
compliant?
It's a component. AFAIK components have no requirements.
I've built many Triac and SCR controllers. Typically they use a Diac to
trigger the on state on each half cycle. The trigger pulse is something
to behold. If not thoroughly suppressed They will trigger other similar
devices in the same building.
I see that this device is the very basic Triac, Diac device shown in
the original book back in the 60s or 70s. "I think" it was a book by
GE, but not sure. It's been a long time.
I started with a basic circuit for a 3 phase, resistive heater(furnace)
The first try was like a Keystone cops movie. Turn one section up.
All OK. Turn the second section up...The first may increase or decrease
as the second one goes up. Add the third section. Both the 1st and 2nd
sections may go up or down, or...one may go up and the other down.
My amp uses a Triac, soft start. You can hear it on every receiver in
the station as a 120 cycle series of pulses going BBBuuurrrrrppp. as it
starts, but it's only a couple seconds. However, that's typical of both
Triacs and SCRs with out filtering.
Fortunately, no one sells one (that I know of) with a non zero crossing
turn off. That takes a reverse pulse that momentarily reduces the
current to a very low value. I don't know if that could be suppressed.
73
Roger (K8RI)
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