SCR's: Sub S8025R for S8006L?

[llilillill]

I'm working on an electric fence charger which has two shorted SCR's. One is a non-isolated 800V 25A (S8025R). The other is an isolated 800V 6A (S8006L).

If I understand the circuit correctly, the gate of the 8006 is connected to one output of a HCF4024BE ripple carry binary counter. The cathode of the 8006 is connected to the gate of the 8025. Therefore, it appears to me the the 8006 is being used to turn on the 8025.

Is there any reason why I couldn't substitute an 8025 in place of the lower amp 8006. The only real differences I can see on the datasheet is the amperage rating and the fact the one is isolated and the other is not (note that neither SCR's mounting tab is used). Digikey has plenty of the 8025's but doesn't stock the 8006 for some reason.

TIA,
Jim
(who knows just enough to be dangerous )

 

[Nigel Goodwin]

Check the gate current requirements, usually smaller SCR's are more sensitive.

 

[llilillill]

The minimum trigger current for both SCR's is 1 milliamp. The only difference is the max trigger current in which case the 8025 is rated at 35 mA versus the 8006's 15mA. This is what leads me to believe I could just substitute the higher rated 8025.

I guess they really aren't all that expensive and trying the higher rated unit shouldn't let any smoke out of the board.

Thanks,
Jim