# Field testing thyristor/scr modules

#### Mayfield

Joined Apr 1, 2013
3

Joined Jul 18, 2013
25,212
I have always used the method shown in my OLD GE SCR circuits manual.
Use a LV, 6vac to 10vac, and feed the anode with one transformer conductor, the cathode to a suitable incandescent lamp, connect 100Ω resistor from anode to trigger and the lamp should light when ever the resistor is connected.
The other side of the lamp to the other LV conductor.

#### Mayfield

Joined Apr 1, 2013
3
I have always used the method shown in my OLD GE SCR circuits manual.
Use a LV, 6vac to 10vac, and feed the anode with one transformer conductor, the cathode to a suitable incandescent lamp, connect 100Ω resistor from anode to trigger and the lamp should light when ever the resistor is connected.
The other side of the lamp to the other LV conductor.

So maybe doing something like this (picture below) I have been reading the datasheet on the TT61N14KOF and where is says gate trigger voltage max 1.4V is that the max voltage for the gate? I'm just not sure what voltages I can use without damaging the scr

Joined Jul 18, 2013
25,212
You must use an AC source only if you want to see it switch on and off.
Use 100Ω resistor

#### DickCappels

Joined Aug 21, 2008
8,710
The voltage at the gates are determined by the current and the nature of the internal diode junctions involved. As long as you have a resistor to deliver the right current from you (AC) voltage source the gate voltage will be fine.

#### Mayfield

Joined Apr 1, 2013
3
You must use an AC source only if you want to see it switch on and off.
Use 100Ω resistor
The voltage at the gates are determined by the current and the nature of the internal diode junctions involved. As long as you have a resistor to deliver the right current from you (AC) voltage source the gate voltage will be fine.

Thanks for the help I really appreciate it although I'm a little confused as to why an AC voltage is required to effect a start/stop arrangement similar to a on/off hold in relay such as something an electrician would wire in for direct on line motor starter?