[sdiy] Transformer question

[Metzger, Michael A]

Bert,
I've got one of those Braun electric toothbrushes. The bottom of the toothbrush
handle fits onto a little nub that sticks up from the recharger/base. The nub
almost certainly contains one end of the transformer core. No, I'm not going to
take mine apart.  :o)  The nub might contain the primary winding, too, but it
looks pretty small. In any case, to duplicate this you want to use one iron bar
(not two) as the core. Wind the primary coil around one end of the core. Leave
space on the other end for the secondary:

	| |
	| | Core
	| | 
	| |
     _____
     _____   Fixed Primary Winding - toothbrush base
	| | 

Now wind the secondary so that it has no core, like a donut. Slip the secondary
onto the long end of the core and VOILA! One quick & dirty Braun-style
transformer!

	| |
     _____
     _____  Removable Secondary Winding - toothbrush handle
	| |
	| |
     _____
     _____  Fixed Primary Winding - toothbrush base
	| |


I am sure there are plenty of people here who can tell you how to optimize it.
Mike




-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Glen
Sent: Thursday, July 22, 2004 2:36 PM
To: Bert Schiettecatte; synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] Transformer question


At 08:25 AM 7/22/04 , Bert Schiettecatte wrote:

>Mmm.. I am wondering now whether I could implement my transformer by
>creating 2 PCBs with spiral inductors and bringing the PCBs close to
>each other. I wonder how efficient that would be and up to what distance
>that would work..

If you're planning on simply etching some spiral lines on the PCBs, and
calling them inductors, you won't get very far with this idea. You really
need some sort of iron or ferrite cores, with a lots of wire wrapped around
them.

later,
Glen