1948 Zenith cobra record player pickup circuit? - UK Vintage Radio Repair and Restoration Discussion Forum

John.Griffin · 8th Jan 2018, 3:33 pm

Hello and thank you for any help!

I’m have an old 1948 Zenith Cobra 78 rpm record player which I’m trying to renovate. It’s doesn’t have any of the original amplifier but the turntable is in good condition so I’m fitting to to a new case and trying to use the original cartridge and needle which is a coil type.

The coil in the cartridge is part of a radio frequency oscillator circuit which is than converted to voice of amplification.

I need to make a modern circuit which does the same thing with the same cartridge? It would be great if it ran on 5 or 12 volts.

I’m ok with digital circuit design but this is way over my head!

Has anyone seen this designed already that I could copy?

Thank again for any help!

John

Herald1360 · 8th Jan 2018, 5:09 pm

Some interesting/relevant info here:

http://antiqueradios.com/forums/viewtopic.php?t=163966

and here:

http://www.antiqueradios.com/forums/...p?f=9&t=323289

Maybe you could do it with FETs but easiest might be to copy original and use "toobs".

John.Griffin · 13th Jan 2018, 5:39 pm

Thank you!

I think upgrading to a modern cartridge might be the best option!

John

8th Jan 2018, 3:33 pm	#1
John.Griffin Retired Dormant Member Join Date: Jan 2018 Location: Capestang, Hérault, France Posts: 2	1948 Zenith cobra record player pickup circuit? Hello and thank you for any help! I’m have an old 1948 Zenith Cobra 78 rpm record player which I’m trying to renovate. It’s doesn’t have any of the original amplifier but the turntable is in good condition so I’m fitting to to a new case and trying to use the original cartridge and needle which is a coil type. The coil in the cartridge is part of a radio frequency oscillator circuit which is than converted to voice of amplification. I need to make a modern circuit which does the same thing with the same cartridge? It would be great if it ran on 5 or 12 volts. I’m ok with digital circuit design but this is way over my head! Has anyone seen this designed already that I could copy? Thank again for any help! John Attached Thumbnails

8th Jan 2018, 5:09 pm	#2
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: 1948 Zenith cobra record player pickup circuit? Some interesting/relevant info here: http://antiqueradios.com/forums/viewtopic.php?t=163966 and here: http://www.antiqueradios.com/forums/...p?f=9&t=323289 Maybe you could do it with FETs but easiest might be to copy original and use "toobs". __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O Last edited by Herald1360; 8th Jan 2018 at 5:15 pm.

13th Jan 2018, 5:39 pm	#3
John.Griffin Retired Dormant Member Join Date: Jan 2018 Location: Capestang, Hérault, France Posts: 2	Re: 1948 Zenith cobra record player pickup circuit? Thank you! I think upgrading to a modern cartridge might be the best option! John