Triac Efficiency

Seriously, I'm not seeing 15A relays on Digikey for less than around

mandag den 5. juni 2023 kl. 20.45.03 UTC+2 skrev Cursitor Doom:

Digikey qty ! forty eight cents: J1071AS5VDC.36 RELAY GEN PURPOSE SPST N.O. 15A Plus a bunch more

Ed

Okay, thanks, Lasse, I got 'em now. They're a bit more expensive in Yurp, but not by much. Well, I stand corrected, then.

Please do not go the the Digikey site. The shock may be harmful to your health.

A hard fast-rise gate pulse turns the whole chip on all at once.

A slow trigger rise can create a hot spot that spreads slowly and may fry the silicon before it does.

If the load is inherently current-rise limited, like an inductor maybe, it's usually OK.

There must be app notes about this.

Yes.

Sorta. A triac is going to drop a good volt whenever it’s on, so you can’t do too much about the losses.

It also has a fair amount of silicon for its dissipation, so its datasheet power rating will be reasonably honest, unlike your average FET’s. (We’re looking at you, IR.)

As JL said, it’s dI/dt that kills them, and soft triggering makes that much worse.

Cheers

Phil Hobbs

And a circuit like this is the very epitome of 'soft triggering' but you see them all over the place. I guess they're okay for low power control:

XU1 N002 N004 0 2N5568 R_variable N001 N003 1k C1 N003 0 0.47µ V1 N001 0 SINE(0 230 50) Rser=4 R_load N001 N002 28 R3 N004 N003 100 D1 0 N004 1N750 .model D D .lib C:\users\bruno\Documents\LTspiceXVII\lib\cmp\standard.dio .SUBCKT 2N5568 1 2 3

• CONNECTIONS: MT2 G MT1 QN1 5 4 3 NOUT QN2 11 6 7 NOUT QP1 6 11 3 POUT QP2 4 5 7 POUT DF 4 5 DZ OFF DR 6 11 DZ OFF RF 6 4 40MEG RT2 7 1 52.8M RH 6 7 75 RGP 8 3 54.5 RG 8 2 26.4 RS 4 8 52.6 DN 9 2 DIN RN 9 3 27.8 GNN 6 7 9 3 38.8M GNP 4 5 9 3 51.2M DP 2 10 DIP RP 3 10 16.2 GP 7 6 10 3 26.1M .Model Din D (IS=53.5F) .Model Dip D (IS=53.5F N=1.19) .Model Dz D (IS=53.5F N=1.5 IBV=10u BV=400) .Model Pout PNP (IS=53.5F BF=5 CJE=235P TF=25.5u) .Model Nout NPN (IS=53.5F BF=20 CJE=235P CJC=46.9P TF=1.7u) .ENDS .tran 0 1.2s 1s 1m

• Value of C1 is largely irrelevant. R1 needs to be a 20k pot in series with a 1k fixed resistor to give the full power range. .backanno .end

Whereas Mouser is harmful to my wealth. Nothing to choose from there at all for under 15 bux.

My very first search hit:

That's why 'incandescent only' labels are used. With non-resistive loads, turnon also is problematic.

mandag den 5. juni 2023 kl. 20.01.47 UTC+2 skrev John Larkin:

yeh, this one looks nice at 8A, until you look at figure 2

I don't see your circuit.

Yeah. Luck beats skill any day. You just don't know which days those will be.

Interesting. It is rated to switch DC too! What will they think of next?

There's a shop in Fremont that will anodize infinite heat sinks.

Not in Yurp I'm afraid. Looks like all real choice stuff is only available in the US, despite the fact that Mouser claims to have bases elsewhere, it's clear they haven't.

Strange. Many of the relays are manufactured in yurpville. And surely you can import Chinese relays as easily as we can.

But it takes forever.