Transistor radio

Thread Starter

Robin Mitchell

Joined Oct 25, 2009
821
Hi guys

I really want to design my own radio but I have this biggy problem. All the radio designs i have seen (both transistor and crystal) need to be connected to the ground. Great, i want one that you can just carry and use.

I cant find any designs for this so does anyone know how to make a radio that DOES NOT CONNECT TO THE GROUND!!!!

Thanks :)
 

SgtWookie

Joined Jul 17, 2007
22,201
The ground symbol as used in electronics does not necessarily mean earth ground; it is the 0v reference point for the circuit.

All ground symbols used in the circuit should be considered to be at a potential of 0v, which also implies that they are connected together.

In some circuits, you may have several different grounds; for example digital, analog, and power grounds. Mixing these types of grounds together can cause considerable problems; for example connecting a digital or power ground to the ground in an analog circuit is somewhat analogous (sic) to inviting a punk band to play a concert in a library. :eek:

In cases like this, the analog, digital and power grounds might be kept completely isolated from one another, and the circuits connected via optocouplers, transformers or other methods.
 

SgtWookie

Joined Jul 17, 2007
22,201
Why don't you post links to one or more of these schematics, or post the schematics?
 

Audioguru

Joined Dec 20, 2007
11,251
The super-regen "FM radio" by Patrick Cambre is a simple piece of junk. It is missing most of the parts of a real radio.

The crystal radio does not have the many amplifiers in a real radio so it needs a long wire antenna and an earth ground.
 

SgtWookie

Joined Jul 17, 2007
22,201
Last edited:
Hi Mitch,
I don't exactly know when you have posted your comment. I am not sure whether you require any assistance at this point of time or not. I have no idea whether you have initiate to design your own radio. It seems to me that you have not started yet but before you could start you want to know the ground rules. Your major concern is to design a radio which does not connect to the ground. I am not a gizmo freak person that I can give you any advice. Though I have some technical sources and if get some positive reply, I will surely get back to you.Cheers.
 

Wendy

Joined Mar 24, 2008
21,840
Commercial models can do it with as few as 5 transistors, but they also have some dedicated parts, which can be a real pain to get.

Another approach is a simple educational kit. They aren't expensive, and go through the basics. You can build a more advanced radio from there. When I was learning electronics the 300 in 1 projects kit my Dad bought us kids one Christmas was a joy.

There is also another type of receiver that works pretty well, and that is regenerative. Regenerative is an old concept, it uses fewer parts and works pretty well. It also tends to jam the same signal for everyone else in the area.

Have fun.
 

MaxSmoke

Joined Oct 29, 2009
35
For a really simple radio that demodulates just AM on the MF band, 300KHz to 3MHz, try using the Tuned Radio Frequency (TRF) receiver chip MK484.

The MK484, a three terminal TO92 package device, was previously known as a ZN414. A circuit based on the radio can be portable and you will find plenty of information on the internet for this device.
 
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