Need help with adapting AM/FM radios

kimbear

Member

• May 12, 2021

• #1

I would like to adapt standard AM/FM radios with a circuit that sweeps the radio thru either the AM or FM band (Depending on if the radio is in the AM or FM mode). The speed of the sweep needs to be adjustable, and needs to be able to be added to most solid state radios.
Whatcha think??

I have the attatched schematic, (not from me) but I dont know what to think of it.

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• May 12, 2021

• #2

It would need to be an electronically tuned AM/FM radio (with varactor diodes), most just use multi-pole variable capacitors.

 

gophert

Well-Known Member

Most Helpful Member

• May 12, 2021

• #3

Why not buy one? Sweep/seek is a common feature on modern radios.

 

kimbear

Member

• May 12, 2021

• #4

Can Variactors replace the Varicap?

 

kimbear

Member

• May 12, 2021

• #5

gophert said:

Why not buy one? Sweep/seek is a common feature on modern radios.

Click to expand...

I do noit want it to stop at stations

 

gophert

Well-Known Member

Most Helpful Member

• May 12, 2021

• #6

kimbear said:

I do noit want it to stop at stations

Click to expand...

Then add some masking tape to keep the seek button pressed.

 

kimbear

Member

• May 12, 2021

• #7

I would like to be able to be added to units that have a Variable capacitor tuning. Maybe someone can help me with adding variactor tuning to Capacitor tuned circuits??

 

audioguru

Well-Known Member

Most Helpful Member

• May 12, 2021

• #8

Every radio will use different variable capacitor values.
You must design a circuit to match the existing variable capacitors (most radios has 3 variable capacitors per band).
You must disconnect and remove the existing variable capacitors to add your varactor circuit.
Why sweep the tuning?

 

kimbear

Member

• May 12, 2021

• #9

May we chat in private Uncle Scrooge.
I may be mistaken, as I so usually am, but most radios seem to have the standard dual , or center tapped Variable capacitor. Once I find a radio that works, I will probably use the same model of radio

 

Ylli

Active Member

• May 12, 2021

• #10

Trying to build a "Spirit Box"?

 

kimbear

Member

• May 12, 2021

• #11

You bet your furry ass YLLi

 

audioguru

Well-Known Member

Most Helpful Member

• May 12, 2021

• #12

Instead of your impossible "reolace the variable capacitors with varactors" idea, it would be more suitable to design and order new parts for a varactor tuned radio. A lot of work.