Simple SW receiver on 3V?

[aurelZ]

Hi folks!
I was looking into circuit of Shortwave receiver which
work stable and solid on 3 V...mean 2x1.5V battery.
I saw many circuits on net and on youtube but most
of them use 9V battery ,which from my point have small time
of duration.
thanks in advance!

 

[Tha fios agaibh]

You could just add boost converter like the TL496 to a 9v circuit.

 

[Audioguru]

Short Wave radios were used a long time ago so their circuits are old.
An old audio amplifier circuit that uses a 3V supply and an 8 ohms speaker will produce only 0.05W of power. As loud as an earphone. When the battery voltage drops to 2V as it is used then there will be no sounds.

If a radio is designed to use a 3V battery today then it will use a modern class-D bridged circuit in a PAM8403 audio amplifier IC. When its battery drops to 2.5V then its output power will be 0.5W in each of its two 4 ohms speakers.

 

[aurelZ]

-You could just add boost converter like the TL496 to a 9v circuit.
Hi
so you think that i can use DC-DC upverter..
but that would just complicate things.
Also i mean use fat 1,5V battery not tiny AA or AAA
so receiver should work long time with low current consumption.

 

[BobK]

There is no reason a 3V would last longer than a similar sized 9V if outputting the same power. In fact, it might be the opposite unless a class D amp is used.

Bob

 

[Audioguru]

Batteries have part numbers. A tiny 186 button cell is 1.5V. The 1.5V cells in a 9V battery are AAA. Then the larger 1.5V cells are AAA, AA, C and D.
You select the chemistry (alkaline?) then their datasheet tells how many mAh they have for their capacity.

If you want a receiver battery to last for a long time then the current used by the radio must be low or the battery must be large.
To use low current then the receiver loudness must be low (earphones).

 

[aurelZ]

Ok
leave aside batteries....
So is here anyone who can recommend me which type
of SW receiver to build?
Regens ...all types are not very much stable
Maybe Direct conversion are better with and much stable.
there are too many designs published?

 

[Harald Kapp]

You may have a look at the SI473x chips which operate down to 2 V.
You will need an additional controller chip (microcontroller).

I also stumbled across this chip. No separate controller required.

 

[TCSC47]

I presume you are thinking 9V means you will use a PP9 which have a reputation for not lasting. However a modern alkaline PP9 can last quite well, particularly if your radio uses headphones instead of a power amp and speaker. Alternatively you can buy rechargeable PP9 style batteries but they can be pricey particularity if you need to buy a charger as well. Thirdly you could use 6 x AA or AAA in a battery holder if you are not bothered by the bulk. Then you could use any of the 9V designs.

However, I came across this simple looking receiver which looks nice. It all depends on the performance you want.

http://www.circuitstoday.com/single-transistor-radio

This design is for the medium wave. No details are given on how to construct the tuning coil apart from it being 0.35 mH and being centre tapped. A bit of research on line will tell you how to wind one for the short wave frequencies.

 

[aurelZ]

Thanks TCSC
This design is really primitive but should work with not god
selectivity .

 

[BobK]

That is basically a crystal set with a 1 transistor amp.

Bob

 

[Audioguru]

The simple circuit is missing sensitivity, selectivity and automatic gain control that every simple super heterodyne AM radio circuit has.

 

[TCSC47]

I don't know if this is your first radio build, but being simple it is more likely to be successful. If you want a more sophisticated design, then 9V supply gives the designer more latitude in their design, so I would ask if it really has to be 3V?

 

[Externet]

From many available in the market :
----> https://www.walmart.com/ip/Kadell-P...MIifntz4_v4wIVlP_jBx0czQ6NEAQYASABEgKxN_D_BwE

----> https://www.walmart.com/ip/Portable...MIifntz4_v4wIVlP_jBx0czQ6NEAQYBCABEgKC5_D_BwE

I have a couple of these available , new in box :
----> https://www.amazon.com/IdeaWorks-FB...=2025&creative=165953&creativeASIN=B00R6TTTBO

 

[aurelZ]

It is not point in - I can buy radio than
can i build it ..there is no fun in buying
but building process is something more ...

 

[aurelZ]

so I would ask if it really has to be 3V?

Yes it must be build with 3V battery to be portable and
with larger A battery to last longer..

 

[Martaine2005]

I will ask again, why it must be 3v?. A pp9 is portable too.
Sometimes a proper explanation of what you are trying to do yields positive responses.
So far in all your posts, is about old transmitters and receivers. Is there a particular reason you choose old technology?.

 

[aurelZ]

I don't get it why you asking this again?
it is perfectly clear to anyone that A celles have longer life and can
deliver more current than 9V batteries.

I see that most of "experts" here like to talk,talk,talk,,,,
without giving real help to one who ask question.
Why is that ?

Old transmitters,receivers ..what is old ?
Or why everything must be digital?

 

[aurelZ]

And again ...
no naswer or suggestion..
just another question ...hmmmm!

 

[aurelZ]

And again ...
no naswer or suggestion..
just another question ...hmmmm!
oh yeah !

...like a rock song ?