Data requested for BAY83 diode (1969 vintage) - UK Vintage Radio Repair and Restoration Discussion Forum

Robsradio · 20th Jan 2019, 10:16 pm

Evening
I have a clock which is a 'kick rewind' type and has a solenoid coil with this BAY83 diode across it for back EMF quenching. The diode is short circuit and whilst I know any high voltage diode will perform in this role, does anybody have data on this diode please, the date code is wk20 1969.
Thanks in anticipation
Rob

Terry_VK5TM · 20th Jan 2019, 11:27 pm

While I can't dig up a datasheet at the moment, an article in VHF Comms magazine lists the 1n914/1N4148 as suitable substitutes for the BAY83, which will put it in the silicon 75v 100mA area (although I have seen a 300mA rating in a datasheet for 4148's recently).

Robsradio · 21st Jan 2019, 11:00 am

Thanks Terry, that was probably what I was going to use, but really wanted to know BAY83 voltage as it is used to quench back EMF from a coil on 24v dc, so I am not certain that 75v will be enough?

Terry_VK5TM · 21st Jan 2019, 1:23 pm

75v is more than enough.

The flyback voltage across a coil with a diode connected wont be any more than the forward voltage drop of the diode itself and then only for a matter of milliseconds.

If your still worried about it, use a 1N4004 or 1N4007.

Robsradio · 21st Jan 2019, 1:50 pm

Fair point, hadn't really thought about it in those terms, I got hung up on the open circuit potential, I will fit a 1N4148, and it also resembles the BAY83 so will look right too

julie_m · 21st Jan 2019, 3:32 pm

The maximum reverse voltage across the anti-kickback diode will be equal to the "HT" rail of the circuit (since the diode is reverse-biased most of the time), and the maximum forward current through the diode will be equal to the operating current of the relay (since that is what was flowing at the moment before it was disconnected, and coils behave as though the electrons in them have inertia, so will try to maintain that current).

20th Jan 2019, 10:16 pm	#1
Robsradio Heptode Join Date: Nov 2010 Location: Isle of Wight, UK. Posts: 557	Data requested for BAY83 diode (1969 vintage) Evening I have a clock which is a 'kick rewind' type and has a solenoid coil with this BAY83 diode across it for back EMF quenching. The diode is short circuit and whilst I know any high voltage diode will perform in this role, does anybody have data on this diode please, the date code is wk20 1969. Thanks in anticipation Rob

20th Jan 2019, 11:27 pm	#2
Terry_VK5TM Nonode Join Date: Oct 2010 Location: Tintinara, South Australia, Australia Posts: 2,339	Re: Data requested for BAY83 diode (1969 vintage) While I can't dig up a datasheet at the moment, an article in VHF Comms magazine lists the 1n914/1N4148 as suitable substitutes for the BAY83, which will put it in the silicon 75v 100mA area (although I have seen a 300mA rating in a datasheet for 4148's recently). __________________ Terry VK5TM https://www.vk5tm.com/

21st Jan 2019, 11:00 am	#3
Robsradio Heptode Join Date: Nov 2010 Location: Isle of Wight, UK. Posts: 557	Re: Data requested for BAY83 diode (1969 vintage) Thanks Terry, that was probably what I was going to use, but really wanted to know BAY83 voltage as it is used to quench back EMF from a coil on 24v dc, so I am not certain that 75v will be enough?

21st Jan 2019, 1:23 pm	#4
Terry_VK5TM Nonode Join Date: Oct 2010 Location: Tintinara, South Australia, Australia Posts: 2,339	Re: Data requested for BAY83 diode (1969 vintage) 75v is more than enough. The flyback voltage across a coil with a diode connected wont be any more than the forward voltage drop of the diode itself and then only for a matter of milliseconds. If your still worried about it, use a 1N4004 or 1N4007. __________________ Terry VK5TM https://www.vk5tm.com/

21st Jan 2019, 1:50 pm	#5
Robsradio Heptode Join Date: Nov 2010 Location: Isle of Wight, UK. Posts: 557	Re: Data requested for BAY83 diode (1969 vintage) Fair point, hadn't really thought about it in those terms, I got hung up on the open circuit potential, I will fit a 1N4148, and it also resembles the BAY83 so will look right too

21st Jan 2019, 3:32 pm	#6
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Data requested for BAY83 diode (1969 vintage) The maximum reverse voltage across the anti-kickback diode will be equal to the "HT" rail of the circuit (since the diode is reverse-biased most of the time), and the maximum forward current through the diode will be equal to the operating current of the relay (since that is what was flowing at the moment before it was disconnected, and coils behave as though the electrons in them have inertia, so will try to maintain that current). __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.