1. Home
  2. Electronics Down Under
  3. I can't get SCR's to work

I can't get SCR's to work

Has anyone been having issues with SCR's (silicon controlled rectifiers)?

I've been trying a couple of different ones, and they just won't work for me!

I've viewed some schematics with SCR's in them, and it seems you can just connect them up like transistors... seems simple. A resistor connects to the gate of the SCR, and you connect a load (such as an LED). So why wouldn't they work? Is there a trick to it? I've tried connecting them both ways and still nothing.

I am using a 12V supply. I've tried various resistor values (for the gate) such as 10K, 2K and 1K. Attempting to trigger it fails.

I've tried a couple of SCR's from Jaycar Electronics, namely the C106B and C106Y. I can't even get an LED to light up!! Can anyone make a suggestion? It seems I am just wasting money on these dumb devices. Thanks. + | LED | [] 560R | Trigger (+) -----====------SCR Resistor | | -

Reply to
Jason S
Loading thread data ...

"Jason S"

** You real sure you know where the Anode, Cathode and Gate leads are ??

............ Phil

Reply to
Phil Allison

gate)

Here's an example test circuit - what you are doing seems to be correct though maybe the resistor value is incorrect. I don't have the data sheet for yours on hand, but the circuit referenced gives 270 Ohm as the resistor value. Have you tried one that low?

Ken

Reply to
Ken Taylor

2 things I can think of -

1) is the SCR and LED connected the right way around?

2) is the current drawn by the LED sufficient to latch the SCR on?

Try this circuit below it should show you if the SCR is working. Use a normally open push button switch to trigger the SCR and once triggered the

12V globe should continue to illuminate even after the trigger voltage is removed.

+12V -------------------- | | | | | 12V 6W globe | | | | anode / ----- \ R \ / / - | gate / | cathode | _|_ / |

- ------- -------- | switch

R = 270 ohm

If this circuit works then the problem with your LED circuit is either component polarity or insufficient current draw.

Reply to
Martin

thanks guys. its fine now.

Jason.

Reply to
Jason S

(snip)

Fess up, wot'd you change?

Reply to
budgie

well i didn't realise the SCR's anode, cathode and gate are in different order compared to that of a transistor. I always assumed the gate was the middle pin. Ha ha. I laughed it off, but I'm relieved now. I've never worked with SCR's before.... First time for everything!! ;-)

Reply to
Jason S

"Jason S"

** So you were starting from SCRatch ??

........... Phil

Reply to
Phil Allison

Tranny with an anode, cathode and gate?? :-)

You'll find that transistors have their pins in different orders as well. Some will be Collector, Emitter, Base whilst others are Collector, Base, Emitter... and so on..

Sounds like you could make use of a transistor reference guide that has the pinouts included.....

Reply to
Martin

u could say that. Jason.

Reply to
Jason S

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.