3rd June 2012 11:57
Alan,
Though this is an older project of yours, I wanted to say that you could use a LM10 Op Amp to make a nifty 1.5V audio amp with plenty of power. I have used this IC extensively for all kinds of spy circuits. I am in the process of making several versions of this MK4848 receiver for fun. Bowood electronics in the UK has a complete Kit for $9. Here is the link if you are interested. They also will sell you the circuit bd. separately if you e-mail them. http://www.bowood-electronics.co.uk/product_info.php/am-radio-project-practical-wireless-magazine-p-1051
Attn: Will
Regards, Jamie
10th May 2008 19:04
David,
Yeah the MK484 is a great chip. I've never tried it much above 80 metres, but most samples seem to be usable on the lower HF bands. I've had some take off at VHF with a poor layout, but shortening the high impedance side of the tank wiring fixed it.
Where did you get the hearing aid receiver from?
Regards,
Alan
10th May 2008 00:27
I like this circuit & the mk484, I built a shortwave receiver using one that got up to 7.0 mHz It broke into oscillations at that point, but I could hear China on it. I use a receiver intended for hearing aids (1k ohm, Knowles 1606) which can be used without an audio amp.
13th March 2008 11:48
Alain,
I'm glad you like my little AM radio. It is a lot of fun. I use it very often, on the ferry on my way to and from work. The circuit is very simple and easy to build.
To read the text in French try Google translation. The machine translation isn't perfect, but is generally usable.
Regards,
Alan
13th March 2008 06:16
Very good! I do'nt understand in totality, but the schemas are easy. I am Frenchman and my English spoken is old 45!.. Congratulations for your work. Good luck!
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25th October 2013 23:35
Austin wrote ...
Hey Alan,
I've built more MK/TA receivers than I've had take away dinners. I like the LF1016 flat bar ferrite rod very much it is such a quality piece of hardware, and even with the thinnest copper wire (scavenged from old reed relay coils) I still get great reception o all local sup here in Brisbane. A well constructed will pull in 12 stations, including 1656Khz - Voice of Chine, and 1701 - Radio Brisvaani, a Hindi only speaking 'narrowcaster' at the top of the dial.
One thing you forgot to mention, was the exact number of turns that you used on the coil. For these flatbar roda dnapvc tuner caps, I usually wind around 80 turns, with both sections A and O, of the cap connected, and both trimmers at full mesh.
If I use my largest rod (about 6.5" in length and 3/8" diameter, with a litz wire coil (litz can be acavenged from old radio and TV IF transformers, and it's made to go well at RF) then I can pick up half a dozen country stations - most of them are either in western Qld., r in northern NSW, but the ;skip; has to be exceptional to get those ones.
I've actually made these AM receivers up in a match box, and even better still - a Tic Tac lolly box. There's still a pic online.
Austin Hellier