# DC output of DC-controlled SSR does not turn off in simple circuit

The following simple circuit turns a LED ON/OFF. It includes:

• DC power supply 12V (EDR-120-12)
• SSR (rated for DC input and output, DR10D12, datasheet)
• LED, 400mA, 2.85V forward (L2-MLN1-S, datasheet)
• resistor 50 Ohm
• pushbutton (PVA6LRE21241, datasheet)

My problem is that the SSR output remains ON and can only be turned OFF with turning the power supply OFF.

When the pushbutton is ON:

• the small LED of the SSR is ON
• the LED is ON and the measured current flowing through it is 198 mA (supposed to be 195 mA = (12 V - 2.85 V)/47 Ohm)
• when there is no load at the SSR output, the resistance across the SSR outputs (1/L1, 2/T1) is 0 Ohm (and my multimeter says it is the same potential)

When the pushbutton is OFF:

• the small LED of the SSR is off
• the LED is ON and the measured current flowing through it is 185 mA
• when there is no load at the SSR output, the resistance across the SSR outputs (1/L1, 2/T1) is 3 MOhm

With the SSR LED turning correctly ON and OFF I believe that the issue is on the output side.

I do not understand where these 185 mA come from when the pushbutton is OFF. (I think the 13 mA difference (198 mA - 185 mA) is the small LED of the SSR turning ON and OFF).

I've read about possible solutions (use a bleeder resistor in parallel to the load to remove a leaking current?) but I am still not sure I understand what is happening here, so I thought I would ask a clear question here for the record.

Thanks for any help

Edit: for clarity, removed the circuit for the LED illumination of the pushbutton

• "Is this SSR designed for DC?" from @user253751. Yes it is:

Diagram of the SSR with DC control input and DC output.

• The datasheet notes that in the off state, there is a maximum leakage current of 0.1mA. That is enough to very slightly light an LED (but not as brightly as the ~20mA that would run through it with the SSR conducting fully). Could you be seeing this faint glow as the LED being on? Dec 15, 2020 at 5:14
• Also, it looks like your terminals are backwards - swap 3/4 and swap 1/2. I think this must be a drawing issue only though, as otherwise nothing should work properly. Dec 15, 2020 at 5:17
• Thanks @SomeoneSomewhereSupportsMonica. It is not a faint glow, I've measured it to be 185 mA, I've edited the post. I've edited the drawing also, thanks, that was only a drawing issue indeed. Dec 15, 2020 at 13:24
• That looks you have tyristor output. Check carefully the part number or may be label wrong. Dec 15, 2020 at 14:20
• Thanks @user263983. Part number is correct: it is DR10D12, ordered from Digikey, part number CC1767-ND. The printed label on the SSR is unmistakably correct. Dec 15, 2020 at 16:55