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bertus
Moderator
Hello,
What do you mean with variable inductor?
In a radio there is a tuning capacitor.
https://www.petervis.com/electronics/tuning-capacitor/tuning-capacitor.html
Bertus
What do you mean with variable inductor?
In a radio there is a tuning capacitor.
https://www.petervis.com/electronics/tuning-capacitor/tuning-capacitor.html
Bertus
Post an image of the component (< 300 kB).
davenn
Moderator
ohhh Bertus .....
There's also variable inductors ... has been since the beginning of radio
here's a newer version
@Poloko ... please note tho. just because there are 5 (6) pins on the bottom, not all of them may be connected to a coil. 5 or 6 pin (2 or 3 either side) is just the standard former type.
The circuit designer will use what he/she needs what they need for the type of inductor they are designing .... see my next post with the schematic showing multiple variations in the number of pins used
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davenn
Moderator
depends on where in the radio circuit the inductor comes from
you have supplied so little info we cannot help you yet
show the inductor, show a circuit you plan to use it in
if this is just a general enquiry, then there are several ways they would be used/wired into circuit
OK, in this part circuit I used to work on, shows a receiver circuit operating in the VHF band.
there's a selection of 2, 3, 4 and 5 pin variable inductors. The 5 pin inductor is in the middle of the
circuit, labelled T2, just before the Mixer FET
Thanks Dave.
I didn’t know that. I also thought the OP was talking about a ‘canned’ variable capacitor.
Us MUCH younger guys have no chance with our elders experience
Martin
I didn’t know that. I also thought the OP was talking about a ‘canned’ variable capacitor.
Us MUCH younger guys have no chance with our elders experience
Martin
davenn
Moderator
Thanks Dave.
I didn’t know that. I also thought the OP was talking about a ‘canned’ variable capacitor.
Us MUCH younger guys have no chance with our elders experience
Martin
in old tube radios variable inductors were much larger ...
see the two, labelled 2, between the tubes
I cant find a photo of the insides of one of those type
but here's a photo of another old one, They would have an iron or ferrite core on a screw
I still feel the OP was talking about a can. But let’s wait for a response.
Martin
Martin
davenn
Moderator
davenn
Moderator
not sure what your definition of a "can" ?
but the "cans" I have shown are what we would typically be referring to
Ohh I have heard of the really old electrolytic caps referred to as cans
on the other hand ... old radio operators would refer to headphones as "cans"
There's also variable inductors ... has been since the beginning of radio
here's a newer version
I took it to be these immediately.
They often form part of resonnant circuits in the radio, to allow selection of bands, to filter out things that are not in the intended band.
As you can see form the ciruit posted above, there's a bit involved to use them well.
You can use them to make simple RF oscillators.
Maybe google oscillators. and look into some of the different forms.
These were common in transistor radios of the last millenium .
You have to use non-magnetic tools for tuning these.
.You have to use non-magnetic tools for tuning these.
davenn
Moderator
These were common in transistor radios of the last millenium
You have to use non-magnetic tools for tuning these.
and they are still very common in RF electronics
bertus
Moderator
ohhh Bertus .....
There's also variable inductors ... has been since the beginning of radio
here's a newer version
@Poloko ... please note tho. just because there are 5 (6) pins on the bottom, not all of them may be connected to a coil. 5 or 6 pin (2 or 3 either side) is just the standard former type.
The circuit designer will use what he/she needs what they need for the type of inductor they are designing .... see my next post with the schematic showing multiple variations in the number of pins used
@davenn , I know those. They are used as tuned circuits for the oscillator, IF (Intermediate Frequency) and detector circuits.
TOKO and MURATA are well known brands for them.
An example of the connections:
In an AM radio you can possibly find these coils:
Here is an other page with info:
http://www.rfcandy.biz/communication/ifcan.html
Bertus
davenn
Moderator
ohhh I am pleased, you had me worried as you response earlier questioned the existence of variable inductors LOL
