sodler

I have been teaching myself some soldering over the last year, to make and augment some musical instruments, and some other, more unexplainable projects (I’ll come back to those in a later post). My biggest project by far was this; building a dub siren from scratch. Here i have documented my process, and made a guide for anyone who dares to follow in my footsteps.

This dub siren is far from the most simple design. If you want an easy way out, you can find an old birthday card that plays a song, or one of those “mr. T in your pocket” gizmos, and just poke’em with a soldering iron and you’re done(like this one). When i started out this project i had no soldering skills at all, but I had some time on my hands and thus I managed to teach myself the basics in a couple of weeks. It was my Christmas holiday, okay? You make it sound like I was unemployed or something.See the full rubdown after the jump.

Breaking news! If you don’t really want your hands wet with all the soldering and hard work, Korg are now releasing their Monotron synth, which does much the same thing as my dub siren, and for the truly nice price of around $85. Product details here. But you don’t want that of course, no, you want to work hard, making your own from scratch! Right? Then read on.

The Dub siren is based around two 555-chips generating the sound. It has buttons for volume, modulation, waveform, phase and frequency. It has a momentary on button, and also a switch for a «hold» mode. An LED blinks at the waveform rate, and another one to indicate that the hold mode is activated(I skipped that one in my build). Check out the video and schematics at the bottom to see and hear.

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Parts needed

IC’s

  • LM555n × 2 – i used these, but most 555s will probably do.
  • LM741 × 1 – operational amplifier

Pots:

  • 50K × 5

Buttons etc.

  • off(on) push button × 1 – the momentary on button
  • on(on) toggle switch × 1 – permanent on/«hold» switch
  • off(on) toggle switch × 2 – modulation on/off switch & power on/off
  • LED × 1 – 3mm or 5mm, i used a fiver.
  • Either a 9V battery (which will be spent crazy fast), or a 9V wall wart transformer, and a DC socket to plug it in.
  • a big TRS socket for the output. You know, like a guitar plug.
  • LED holders (for extra finesse and glam)
  • IC holders to protect your ICs from overheating when you are soldering. Especially important if your soldering skills are not the best.
  • Knobs for the potentiometers
  • Some cool casing. I used an old barbers box i found at a flea market.

Capacitors:

  • 47μF × 1
  • 47nF × 1
  • 22μF × 1
  • 150nF × 1
  • 10μF × 1

Miscellaneous:

  • A bunch of resistors. Just buy a packet that has all kinds.
  • 2 General purpose NPN transistors (see the circuit diagram below)

If you are scandinavian, and don’t have a store in town that carries the parts, have a look at electrokit.se, where i got (almost) all my parts. Pretty cheap. I later found out Elfa seems to be the industry standard supplier. My experience tells me that buying this stuff online is way cheaper that in a store. And it’s light, so postage is next to nothing. My 555s I had to order from the UK(totalrobots), so i bought 20 so i’ll never run out.

More things to think about

I actually made this siren twice, the first time around I basically had no idea what I was doing, and the result was that if I opened the lid of the siren, or just shook it a little, it would change sound, or most times just stop working. Hopefully not at a gig. So what to do? Build the whole thing back up from scratch of course!

The second time around I was able to take benefit from everything i had learned from my mistakes. For example, the first version used solid core wiring. Kids, stay away from that stuff! It just breaks all the time. I used it because I was so tired from stripping cables with scissors. Instead, use multi-core wiring and just invest in cable stripper pliers, they go cheap.
Secondly, try to make the entire thing one one board, putting all the components as close together as you can. This way you have a way more stable end product, that will not break if you just look at it angrily, like my first one did. As a bonus this makes the whole thing take up less space, abling you to use a smaller casing. I actually overshot it a bit with my casing, i could easily get away with using something half its size. My tip on this is to wait deciding what to use ’till after you finished soldering, so you know how much space you need.
Another thing you need to know about the schematic is; Dave made the IC’s a little confusing. The connection on the top left of your IC does not necessarily correspond with the one on the schematic. I found out what connections are where on the ICs i used (see the pictures above the video), if you use different model IC’s than me you might wanna google the model number and go through some pdfs to find it. If you are in doubt, use my drawings to guide you through it.

Another thing is, your line output is going to be huge on this thing. So right before the last output (on the + wire of course), put a resistor, just experiment with different ohms. If not, you might come with the siren to a party, and when some drunken fool ramples up on stage to mash your buttons, he turns the volume all the way up, and blows every fuse from here to Calcutta.

According to feedback in the comments, you should tie the 22μF smoothing cap’s negative leg to ground. That way you won’t risk blowing it.

You can nick the original schematic from dave on flickr too. Just keep in mind the alterations I mentioned. If you need to learn how to solder, this article is a good primer.
The schematic is at the bottom of the post, alongside some pictures. Just download that, and see if you can make sense of it. Good luck!

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that’s about all I can gather from the schematic. Hope I didn’t forget anything. Just holler in the comments if you have questions, or, you know, comments.

UPDATE: This article has gotten a lot of great comments, so I highly recommend reading through them all, as many of them may answer your own questions.
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