Buying and inductor to make a varitone

[ivanmax]

Hi everybody!!!

Just a little question. Could anybody tell me where I can buy and inductor to build a varitone?

Thanks a lot in advance.

Iván

[thumbs]

I don't know the value of the vari-tone inductor, but Torres Engineering offers a vari-tone kit for $15.95. If the inductor you need is a 1.5 henri, you can get it for $4.95 with the "Torres Famous Midrange Kit". If you find a better source for these, would you please post it?

[David Schwab]

You can get inductors from any electronics part suppliers, like mouser, digikey, jameco, etc.

You can also use audio transformers. The one from RadioShack works ok.

[ivanmax]

Hi,

Thanks a lot for your help. I found this one in Mouser (I believe is the one Dan Torres uses to build his varitones):

42TL021

Will that be fine? The thing has six legs...to be honest I don´t know what to do with so many of them. Has any of you any idea of how to connect this?

Thanks,

Iván

[GibsonLover]

The data sheet is on the link you provided. There is a center tapped primary, and a center tapped secondary. Either use the entire primary, or the entire secondary, and never mind the center taps.

[Mike Sulzer]

Originally Posted by ivanmax

Hi,

Thanks a lot for your help. I found this one in Mouser (I believe is the one Dan Torres uses to build his varitones):

42TL021

Will that be fine? The thing has six legs...to be honest I don´t know what to do with so many of them. Has any of you any idea of how to connect this?

Thanks,

Iván

That transformer has a 3:1 turns ratio; thus, the inductance of the secondary is 1/9 that of the primary. Using half the primary would give you 1/4 the inductance of the whole primary. The inductance of the whole primary is probably about 1 Henry. I am just guessing that based on the 300 Hz low frequency spec and the primary impedance (4K). Probably you want to use the whole primary.

[David Schwab]

In the book Electronics Projects for Musicians, Craig Anderton uses Mouser part 42TM-019 for the inductor. He uses the whole primary, and also has a switch at the tap for half the primary.

The inductor in the Gibson L6-S was a 1/4" steel bolt, with three washer and a nut! They wound two coils between the washers so it was humbucking.

I have the specs around somewhere, but it isn't hard to make.

[thumbs]

Although I've used these things for years, my understanding of them is a little foggy. If I were using a 1.5h inductor, a .033uf capacitor, and a 250k pot, which component (or combination thereof) would determine the frequency of the cut? Which would determine the depth? I don't have a strong background in math. If someone could explain it in layman's terms it would be greatly appreciated.

[David Schwab]

I found this one on the 'net somewhere. This is for a standard Gibson 6-position Varitone:

Position 1--> off
Position 2--> -5db at 1950hz
Position 3--> -12db at 1100hz
Position 4--> -16db at 620hz
Position 5--> -18.5db at 360hz
Position 6--> -21db at 120hz

Position 5 used a .03 cap.

The L-6S guitar used a pot instead of a switch, and a .01 cap.

[ivanmax]

Hi,

Well, I have just bought a Torres kit to make a varitone. When I got it I will post the value of the inductor here. Actually I believe he uses a small transformer.

Regards and thanks,

Iván

[RedHouse]

Originally Posted by ivanmax

Hi,

Well, I have just bought a Torres kit to make a varitone. When I got it I will post the value of the inductor here. Actually I believe he uses a small transformer.

Regards and thanks,

Iván

So what did it turn out to be?

[ivanmax]

Hi,

It is a small transformer with the following writing on its body:

TL021-R

You can find these ones in Mouser.

Regards,

Iván

[GibsonLover]

I measured a Radio Shack miniature output transformer (10K/8ohms) and the primary came out to .8H @ 1KHz. At 120Hz = 2.1H. Obviously, it will vary with frequency, but for anything in the right range, the cap used with the inductor is the part to experiment with. I'm using this set-up with a Telecaster in the neck position, approximating the Varitone 'Position 4'.
The middle position = neck only and the back = Broadcaster Blender (Lollar CC set). Cool, cool, cool.....

[dovedescending]

Originally Posted by thumbs

Although I've used these things for years, my understanding of them is a little foggy. If I were using a 1.5h inductor, a .033uf capacitor, and a 250k pot, which component (or combination thereof) would determine the frequency of the cut? Which would determine the depth? I don't have a strong background in math. If someone could explain it in layman's terms it would be greatly appreciated.

Sorry to raise a dead thread, but I couldn't help myself because this question needed to be answered. The capacitor wired in series with the inductor creates a resonant frequency of a certain value. THe equation is

ƒ=1/ 2π(√CI)

where ƒ is the frequency, C is capacitance, and I is inductance. you can go to Wolfram|Alpha
and search "resonant frequency" for a calculator that will allow you to determine your various noth filters based on your inductor and whichever capacitors you choose. In order to vary the depth of the notch, wire the whole thing up to the tone control as if it was a single capacitor instead of a wad of components. Turning your tone control should vary the depth of the notch.

[thumbs]

dovedescending, thank you for your post and the link. I've built a number of these filters either "by ear" or by copying someone elses design. It will be fun to try again, going for a specific result.

thanks again'

thumbs