Old transformers from a VCR - UK Vintage Radio Repair and Restoration Discussion Forum

Jolly 7 · 27th Jul 2019, 10:02 am

As part of a VCR teardown, I recovered these transformers. Are they called air-core transformers and could they be used for low voltage projects ?

dazzlevision · 27th Jul 2019, 10:22 am

They’re ferrite cored components and look like mains input RF chokes used in the VCR’s power supply.

'LIVEWIRE?' · 27th Jul 2019, 11:16 am

As such these might be useful where such chokes are needed. Anyone have any idea what the inductance of these chokes might be?

turretslug · 27th Jul 2019, 6:17 pm

This type are often cored with something giving high inductance but which also saturates easily and are therefore designed so that the current through each of the two windings cancels the resultant field- typically mains line and neutral in and out, so to speak. I'm assuming that they were from VCRs with SMPSUs, though it's not unheard of for them to be found on the input of PSUs with conventional LF laminated transformers.

Ed_Dinning · 27th Jul 2019, 8:36 pm

Hi, stuff like these is OK for interference suppression, but it implies the VCR had an SMPS.

Much earlier VCRs had proper mains transformers with a multitude of different LV windings
These were great as supply transformers for battery sets, I had an article published in WW in the 70's of just such a unit using one of these transformers.

Ed

Terry_VK5TM · 28th Jul 2019, 2:52 am

Older Hi Fi's that ran with +/- 70V or more rails had rather useful transformers for valve supplies as well.

The input filters as in the OP's post are useful in transformer based LV power supplies as well.

27th Jul 2019, 10:02 am	#1
Jolly 7 Octode Join Date: Feb 2018 Location: Southampton, Hampshire, UK. Posts: 1,061	Old transformers from a VCR As part of a VCR teardown, I recovered these transformers. Are they called air-core transformers and could they be used for low voltage projects ? Attached Thumbnails

27th Jul 2019, 10:22 am	#2
dazzlevision Dekatron Join Date: Sep 2003 Location: Near Swindon, North Wiltshire, UK. Posts: 3,608	Re: Old transformers from a VCR They’re ferrite cored components and look like mains input RF chokes used in the VCR’s power supply.

27th Jul 2019, 11:16 am	#3
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Old transformers from a VCR As such these might be useful where such chokes are needed. Anyone have any idea what the inductance of these chokes might be?

27th Jul 2019, 6:17 pm	#4
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,394	Re: Old transformers from a VCR This type are often cored with something giving high inductance but which also saturates easily and are therefore designed so that the current through each of the two windings cancels the resultant field- typically mains line and neutral in and out, so to speak. I'm assuming that they were from VCRs with SMPSUs, though it's not unheard of for them to be found on the input of PSUs with conventional LF laminated transformers.

27th Jul 2019, 8:36 pm	#5
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Old transformers from a VCR Hi, stuff like these is OK for interference suppression, but it implies the VCR had an SMPS. Much earlier VCRs had proper mains transformers with a multitude of different LV windings These were great as supply transformers for battery sets, I had an article published in WW in the 70's of just such a unit using one of these transformers. Ed

28th Jul 2019, 2:52 am	#6
Terry_VK5TM Nonode Join Date: Oct 2010 Location: Tintinara, South Australia, Australia Posts: 2,339	Re: Old transformers from a VCR Older Hi Fi's that ran with +/- 70V or more rails had rather useful transformers for valve supplies as well. The input filters as in the OP's post are useful in transformer based LV power supplies as well. __________________ Terry VK5TM https://www.vk5tm.com/