radio sequencer

[jean-louise]

I am not sure if somebody has done something similar before, but i always dreamt about it and couldn't find information then.
Some weeks ago, i half-haphazardly stumbled upon a cheap tiny fm radio kit by Franzis that uses a pot instead of a variable capacitor to tune into the stations.
I added a simple sequencer like the one on the "fun with seamoss"-site(40106, 4040 and 4051).
But one could also make it respond to CV via vactrols and so on.
Here's a video with bad picture quality:

http://www.youtube.com/watch?v=Ui5Elu-1Wjc

The radio is not the most reliable, but it's really ok, i think it would benefit from using a stable power source (i am currently using two AA batteries)
I can make the clock go really fast and it still changes stations in time - at least i guess that - it's too fast to be sure.

If it had a name it would be called "Sir Franzis Cage".

I should make a better quality demo soon.
It's kind of hypnotic listening to the changing bits of broadcast. Also good if you're an information junkie and like to listen to 2, 3 or even 8 radio stations at the same time

cheers
jan

[emdot_ambient]

Wait...so each step of the sequence changes the radio's frequency?

Pretty cool!

Too bad it's FM and not shortwave.

[emdot_ambient]

...build one that changes stations fast enough and you end up with a strange kind of radio wavetable synth

[jean-louise]

[synthesist]

sick!

maybe there is also a way to modifie the remote control from a TV.
He or from a playstations joystick pad.
All three devices synced!

[sonic]

I love this! Great job Jean-Louise! For a long time I also had intentions of somehow harnessing all the wonderful sound sources floating through the atmosphere. I think shortwave would be cool because you could then play the weird squeaky sounds you get when you tune between stations. Playing with a shortwave radio when I was a little kid was I think the first time I got interested in electronic sounds.

Does anyone know of a schematic for a radio (shortwave or otherwise) which could be tuneable via a pot / vactrol etc? Are the schematics for the Franzis radios available - I presume they are, seeing as they are kits.

It might also be interesting to use radio waves to modulate different synth modules - perhaps even to modulate the behaviour of a sequencer (not necessarily one which is tuning the receiver itself - that would be craaaazy!)

[jean-louise]

in a hurry:

http://www.elektronik-labor.de/Lernpakete/UKWradio4.html

there are the schematics

[jean-louise]

Thanks for your feedback!

[Dan Lavin]

Jean-Louise, this is great! It's so simple yet no one's done it before that I can think of. That's thinking outside the box!

[emdot_ambient]

The reasons I like shortwave better than FM are:

It's used for non-verbal and non-commercial radio signals (Morse code from ham radio operators, maritime, naval, aviation, military, experimental signals...etc.)

It is extremely long-range so that here in the States we get signals from S. America, Europe, Asia, Russia, Africa...and who knows where, whereas FM is 100% American English (and 95% commercial crap)

It suffers from severe interference from overcrowding on the wavebands, atmospheric disturbances and the like...all of which makes the signals extremely abstract, drifty and interesting! FM may have some in-between station bleed-through, but pretty much anywhere on the shortwave bands is in-between signals at some point in the day...signals drift in and out.

It often sounds like a complete Forbidden Planet-like soundtrack!

I used to spend hours dialing up and down the dial. Very mysterious and bizarre sounding. I have at least 45 minutes of it on cassette tape somewhere...recorded for sampling

[jean-louise]

Dan Lavin:

Thank you very much!
i guess if it really hasn't been done like this before, it's because radios that use potis for the tuning are very rare or so they seem to me..

emdot_ambient:

Yes, i see what you mean. It's been a while since i played around with a weltempfänger/shortwave radio. I figure the result would be more abstract and "radio-like", not so much like the "evolving sample"-character (with additional radio noise) it has now. I think i would like both versions

jan

edit: small correction to make more sense

[ericcoleridge]

Man, that's such a great idea. Thanks for posting this. It would be a great project with a layout for the variable resistor and interface.

I also love the idea of using Short-wave signals-- it does seem like it might offer more variety of sound sources. But, what does one need for short wave reception? On the other hand, there's so many cheap small FM tuners and kits that might be usable.

[jean-louise]

[jean-louise]

Some additional thoughts: It would be good if one could turn off the AFC in order to get more weak/wrongly set signals.
There is a thump on a lot of steps (if the frequency changes). Could this be caused by the AFC?
http://electronics-diy.com/fm-radio-receiver-using-tda7088.php
this is an interesting page, though i do not understand everything yet..
Ok i go back to the datasheet and some light radio theory. I might even learn something

...

Now i changed the resistor R2 from 220k to 36k, this reduces the effect of the AFC. It's a good compromise between tuning stability and freedom. I also had to change R1 to 100 Ohm to get a wider range.

It seems that it's no big thing to replace a variable capacitor with a varicap diode/varactor - at least in some kinds of circuits. So maybe it's no big problem doing it for an AM or shortwave radio (but this is just wild guessing).

I should have read this thread more carefully. it has a link:

http://nomeist.com/voltage-controlled-fm-radio-cv-radio/274

I knew it must have been done before!

cheers
jan

[jumunius]

Amazing! I'm pretty sure this is the original idea that got me into DIY years ago, but at the time I didn't go too far with DIY and consequently I never got around to figuring out how to do it. I'm really pleased and impressed that you pulled it off. If I can ever clear my list of pcbs a bit maybe I can finally try it!

Also, your results sound something like what I imagined, which is particularly exciting.

+1 for trying it with shortwave too -- I hope someone manages that.

[jean-louise]

hey jumunius!
glad you like it -
some more for your ears with better sound


a little compression, little eq

maybe an Attack/Release and/or equing could get rid of the thumps if they are not desired. I still haven't tried how it sounds without AFC.

jan

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radio test.mp3
Description:	radio sequencer, test with audio out. cut at 1:12, after that clock to maximum and back.	Download
Filename:	radio test.mp3
Filesize:	5.64 MB
Downloaded:	853 Time(s)

---

[LFLab]

Tres cool! Reminds of this Buchla polyphonic tuner

[frijitz]

For any hardcore DIYers, here's an example of a simple 3-transistor regen SW receiver.
http://www.circuit-projects.com/radio-frequency/high-selective-regenerative-shortwave-receiver.html
The tuning cap C1 could be replaced with a varicap diode. The varicaps don't give a huge tuning range, so you would need a big ole switchable coil on the input.

I used a regen receiver for years in my ham radio adventures.



Ian

[jean-louise]

Hello Ian,

thank you very much - wow, it's a small circuit!
cool for experimentation, should fit on any breadboard easily

here are more tiny radio circuits, the matchbox version uses a varicap diode

http://www.techlib.com/electronics/reflex.htm

cheers

jan

p.s.: the thumping has nothing to do with the AFC, i am breadboarding a simple vca with attack/release now and see if that helps.
edit: works good, but i think i need to buffer the clock.

[frijitz]

[v-un-v]

[elektro80]

Brilliant idea. I researched this a bit some years ago with some input from EdisonRex. I didn´t do anything with the idea.

BTW.. and possibly off topic..

I remember one circuit that got a lot of press way back and that was the Armstrong 600 Series AM Tuner. Off the top of my head.. it had one huge tunable AM band consisting of LW and MW.. and the only tuning spot was the actual bias voltage to an SMV770. There were mods for it that created an "all waves band" with LW, MW and an extended SW. Very cool!

Armstrong is a well known british brand, but I reckon it is completely unknown in the US and all the press the AM Tuner got was probably contained to european electronics magazines. Mods for it could be installed in your local hifi-nut/DX shop or you could buy mods as kits.. or follow instructions published in magazines.

[elektro80]

Googling the Armstrong 600 AM Tuner will unveil schematics and more. I half expected the device to be too obscure.

The actual model number for the tuner is 623, as this is the standalone FM/AM tuner. They also had a receiver and one FM only tuner. AFAIK, the same AM tuner was used in both the receiver and in model 623.

Right.. here is the Armstrong 600 explained..
http://www.audiomisc.co.uk/Armstrong/600/600page1.html

And here is some about the tuners:
http://www.audiomisc.co.uk/Armstrong/600/600page2.html

AND here they go wild on the AM Tuner! :
http://www.audiomisc.co.uk/Armstrong/600/600page4.html

What I am suggesting is that the Armstrong 623 could be modified to the AM all-waves state and then a control voltage circuit could be designed for the diode bias voltage. The Armstrong gear is collectible but AFAIK the 600 series components can be bought for nearly nothing these days. They usually go into the trash, which is rather sad. By nearly nothing I mean say like 5-15 UK pounds.

[frijitz]

[tombola]

Just wanted to thank Jean-Louise for the inspiration - used the Franzis circuit to make a little FM Radio module for my Eurorack:

http://www.muffwiggler.com/forum/post-673084.html#673084