Hello all,
Need to make a lil bug to run on 5v , Only needs to go very short range.
Seen all kinds of circuits for them on the web, But what i need to know is which transistor package would be more stable in an oscillator circuit the T0-92 or T0-18.
Have any of you guys notice any difference between them.

Frequency stability is mainly due to the quality of the capacitors used in the oscillator. Try to find ones with COG or NPO rating which are temperature compensated. For the transistor, an MPSH10 works well.

If you want lots of stability, look at the NRG push-pull VFO circuit. It uses two transistors, but the stability is remarkable if you use two hfe matched transistors and NPO ceramic capacitors.

Ive got a schematic using mpsh10 if you like it, 2 transistors oscillator and final, but its 9v

Banus - it'll probably run on 5V with minor value changes. Put it up here!

I bought one of these off eBay - http://www.ebay.co.uk/itm/291970155726?redirect=mobile it does a good 300 > 400 metres when listening on a phone radio, but in the Car I've picked it up around 1.5 miles away.

@Albert,

I don't want to derail this thread, but it seemed pointless posting a new thread just to ask this.

What is this? - Is it a copy of one of those push - pull Pantec type things from back in the day? Also, surely this won't do 2W? It looks like it's using audio Transistors like the BD139 or similar - http://www.ebay.co.uk/sch/i.html?_from= ... 1&_sacat=0

NO - nothing to do with the dreadful Pantek things!!! The NRG circuit uses a pair of RF transistors (originally BF 494s) and a row of coils. For a free-running oscillator, it was ridiculously stable. They used to give 50 - 75mW depending on the supply voltage.

Albert H wrote: ↑Fri Feb 17, 2017 9:04 pm NO - nothing to do with the dreadful Pantek things!!! The NRG circuit uses a pair of RF transistors (originally BF 494s) and a row of coils. For a free-running oscillator, it was ridiculously stable. They used to give 50 - 75mW depending on the supply voltage.

No, I didn't mean the NRG, as I know they're OK gear.

I meant what is this on eBay. Is it a copy of a Pantek or that thing that used 2 x 2n3553, or is it something completely different? Surely this can't do anything like 2W? http://www.ebay.co.uk/itm/UKW-Sender-FM ... Swl9BWGmOe

That looks dreadful. It might consume 2W from the battery, but the energy on the required frequency will be accompanied by lots of other frequencies.....

Thanks for the input, would be great if someone does have something that works well on 5v.
I do know the old barney, steve may half frequency oscillator works on 5V as the orignal had a 5volt regulator before the buffer.
Later on some resistors where changed that made it 8V and a MRF237 was added for 4watts output.

I think Albert was pushing for this or something similar:
http://www.veronica-kits.co.uk/lpkit.htm
The blurb says it works down to 6 Volts. That yoke from ebay looks like a pantek style super oscillator, good for a kids toy but it'll drift at the drop of a hat and produce a lot of dirt. Probably has £2 quids worth of parts in it BTW.

Nice one necks.

I thought it looked a bit like one of those Pantek things from the 80s/90s but wasn't sure.