1. Home
  2. Electronics Design
  3. 455kHz IF transformers

455kHz IF transformers

I know these things have practically gone extinct, but I would quite like to find 3x 455kHz 2nd IF transformers (white slug) and a 3rd IF transformer (black slug). I notice others have had difficulty finding them too. None of the usual places has anything at all in this line.

I want to build a theremin for a science lecture so the ability to pull the oscillators well off frequency by stray capacitance is essential. Ceramic resonators just will not do...

I suppose I could wind the transformers by hand, but I think for this application it would be more stable to have three identical ones machine wound rather than DIY. Best I can think of is to go round car boot sales buying up a few dead transistor radios. There must be a better way but I cannot see it at present. Any other ideas?

Thanks for any suggestions of a UK or EU supplier (failing that a US supplier who will export what will be a very small order).

Regards, Martin Brown

Reply to
Martin Brown
Loading thread data ...

formatting link

Leon

Reply to
Leon

formatting link
and search 42IF200 series. They will sell you one to a million, your choice.

They ship across the pond all the time.

Jim

Reply to
RST Engineering - JIm

Dan's Small parts and Kits (a US supplier) has a 3-can set of 455KHz IF transformers; described on the web page at

formatting link
as:

TOKO 3 PIN 455 KHZ IF TRANSFORMER SET. This is a 3 piece set includes 1ST IF YELLOW, 2ND IF WHITE AND 3RD IF BLACK. The size of these are 10 MM. A pin out sheet is provided with the cans. PRICE FOR THIS 3 CAN SET IS $2.50

Dan's ships internationally.

--
Dave M
masondg44 at comcast dot net

I went to a bookstore and asked the saleswoman, "Where\'s the
self-help section?" She said if she told me, it would defeat the
purpose
Reply to
Dave M

Failing all of those suggestions, i could send you two Radio Shack AM trasistor radios..

Reply to
Robert Baer

How does "stable" apply to a _theremin_, for heaven's sakes? ;-)

Hand-winding goes a lot faster with a jig of some kind and a drill. And hand-winding doesn't cause unstable coils, unless you've done a supremely crappy job of winding it. :-)

What if you used some kind of RC oscillator with high resistor values; if it's not sensitive enough at audio freq's, then make a couple at some RF freq, and it plays the heterodyne?

You'd just have to design the two such that one is sensitive to the "antenna", which could be fun. :-)

Good Luck! Rich

Reply to
Rich Grise

Hey - he'd have a ready-made theremin; just string the antenna to the L.O of one and heterodyne it with the other! ;-)

Cheers! Rich

Reply to
Rich Grise

I don't want to make the job any harder than it has to be. I reckon three matched 2nd IF coils for the reference local oscillator, pitch and amplitude oscillators will have similar thermal drift with a bit of luck. There are a lot of adjustable parameters to make it work (or not).

I found a 2nd IF in the right can at the website Leon so kindly posted. When the article was written they were common penny items. The 3rd IF coil still eludes me. Can someone who remembers this stuff tell me how it differs from the 2nd IF (Q/load capacitance etc). I might be able to use a ceramic filter in this position since it is only being used as filter.

The LO is at 455kHz and heterodyne mixed down to audio band. I am not sure to what extent the design depends on magnetic flux linking as well as stray capacitance to work. Entrainment is part of the game.

I expect some amusement.

I have always wanted to build one and now I have the perfect excuse. Then I have to learn to play the Dr Who theme on it.

Regards, Martin Brown

Reply to
Martin Brown

Thanks for this Leon. Looks like they still have something suitable from the Toko range in stock. 10 off pricing while stocks last.

Cheers, Martin Brown

Reply to
Martin Brown

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.