I just put together a slideshow of images of the Dalek build I completed in 2009.

The music is completely produced from old Dalek parts…
[Are you sure about that one? - Ed]

A big thank you to Dave Duca and all the other builders at www.projectdalek.com…

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Or more precisely – how to build a ring mod and light flasher.

[If you are wondering what a Dalek sounds like, take a look/listen here]

The first step I took was to download the manual for the MoogerFooger and find out what all the knobs do. It looks to me like Nick Briggs uses a “secret Dalek factor” as the carrier and feeds this through a traditional ring modulator constructed from 4 diodes and 2 audio transformers.

Luckily there’s a great website that shows you how to build a passive analog ring mod here:

http://www.asciipr0n…gmod/index.html

Follow the directions on the page and wire up the audio transformers:

Audio Transformers

and the germanium diodes

Germanium Diodes

in the characteristic ring arrangement:

Lovely.

Your voice goes in on the red wires, the secret Dalek factor goes in on the green, and Dalek magic comes out of the yellow. (Actually connecting up in any order will make the RM work)

OK now to add the secret Dalek factor.

I don’t like to re-invent the wheel, so if there’s something out there that can *almost* do the job, I will hack away at that rather than design something from scratch.

The secret Dalek factor (as most of you know) is a 30Hz sine wave. So we need to find an audio oscillator that can provide what we need. Fortunately for us, (and Mr Hewlett, *and* Mr Packard), there’s such a thing as a WIEN-BRIDGE oscillator. Rainbow Kits sells a nice one for $not-very-much-at-all.

However, out of the box this kit does not do what we want. It oscillates at a fixed frequency that is too fast. After a bit of RC [1/2PiRC] math it turns out that we need to replace capacitors C1 and C2 with 0.1uF ceramic caps, and resistors C5 and C6 with approx 53.1KOhm.

Alternatively you can do as I did and get a dual gang pot (200KOhm) and turn this till the output reads close to 30Hz.

Great, so we’ve added the secret Dalek factor on the green wires, now we need to add the voice. For this we’ll need a microphone and a pre-amp. Velleman to the rescue here:

This tiny kit goes straight in unmodded.

All that remains is to add the speakers – for this I hooked up to 12v PC speakers to the red wires. Plug it in and hey presto – instant Dalek.

The sound can be improved greatly by feeding the microphone through an EQ effect pedal, boosting the mid-range and cutting the high and low.

Next stop – the light flashers…

-+-+-+-+-+-+

This was tricky. The standard Schmitt trigger that’s on Dalek City is OK, but the lights can get stuck in the “on” position and you have to cough to toggle them off. Also inside the cockpit there’s no visual feedback to what the dome lights are doing. Also the current requirement to flash 2 x 20W halogen lights on 12V is pretty darned high.

Again, I’m just going to mod some existing cheap kits that are readily available. The first kit is the well-known Velleman MK103 sound to LED light flasher:

This works at a mic level input – great for us – and has high impedance so the signal is not really affected. It only light 4 LEDs though which is no where near what we want to power 40 watts of halogen grooviness.

Here’s a picture showing the basic mod:

I replaced the built in mic with two wires which is connected to the mic socket, and the last LED (4) has been removed. You can simply wire this output into an optoisolator (4n29) through a 1K resistor, then use a big power resistor to switch the lights (TIP142, or a Mosfet)

OR…. you can take the Rolls Royce approach and wire the output directly into this little beauty:

The fantabulous Velleman MK114 12v sound to light kit, rated at up to 50 watts at 12v and a brain tingling 100 watts at 24v!

You just plug it straight in and away you go…

Note – the MK103 really likes to be run at 9v, not 12 – so I added a 9v regulator to run it where it wants to be.

I like this solution, there are two parallel transistors and a nice big fuse. It really *looks* like it can handle the power.

So that’s it, your voice mod, light flashing device is ready to be installed in your favourite MkIII travel machine. The lamps I have plugged in are low power, as my PSU cannot put out enough current to drive the two 20w halogen bulbs I just bought. So I need a bigger PSU…

Of course, this is only half of the story.

To really sound like a Dalek you have to adopt the harsh staccato tone, and do a bit of acting…

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Finally got the bugs out of the system…

I now officially declare this project over.

Time to work on something new…

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I’ve been battling (for quite a while) with the steering controller for the full sized Dalek. I was shown these neat servo gearboxes from ServoCity.com. So I went ahead and ordered one for the HiTec 7955 servo.

The modifications to the servo were really very difficult to do, and I hope I never have to do it again! Next time I’ll be ordering one with the servo installed.

…and in the Dalek…

…and my first driving lesson. Speed set to *very slow*

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All of a sudden my DRSSTC Tesla coil stopped working.

It took a long exposure in a darkened room to see the very faint corona around the top of the primary coil – that’s definitely not right.

Ooh that's not good

The coupling between the secondary and primary coils was too tight. So I rewrapped the primary coil tighter and lower than it was before, and that seemed to fix things.

Not sure why that suddenly started to happen, as it’s been working great for about a year.

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…and I guess I use that term lightly.

I’ve been building a MIDI modulator for the DRSSTC tesla coil I put together last year.

One of the problems is tuning a 555 based oscillater to match MIDI note numbers. I played around with Excel for a while, but couldn’t really get anything useful going. So I wrote something in C# to help.

555 to MIDI calculator

This application calculates the frequency of a standard 555 timer in Astable mode based on the values of C, R1 and R2. I split R2 into a fixed resistance (R2a) and a variable resistance (R2b). R2b is controlled via the MCP42100 digital potentiometer that can be hooked up to an Atmel microprocessor very easily.

After calculating a set of frequencies for the 555 timer, it then goes on to calculate the set of frequencies for standard MIDI note numbers.

Finally it compares the legal MIDI note numbers to the table of 555 values, and comes up with the best match for each note in table 3.

I’ve not yet implemented the results in hardware to see how musical it sounds, but on paper it all seems to work well.

The application is a C# solution available here (also contains compiled runnable version).

Update; it does work!

Even thought the sound quality is very flaky – this first run shows the tuning is just about right.

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I’ve been going through all my shelves in the basement and trying to complete as many of the unfinished projects as I can, just to clear some space.

One of the things I needed to do was box up the old Staco Autotransformer I have. I was faced with this:

Hmmmm...

But luckily I found Tim Reese’s webpage that explains how to hook the variac up for both 120/140v output.

http://www.nmr.mgh.harvard.edu/~reese/VariacPage/

So that’s one more project finished.

Green for 120v and red for 140v

Yay!

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I’ve been slowly working away on the Dalek – grabbing a few hours here and there. I’ve got the basic power distribution system in – unfortunately the drive system is 24v, and other parts need 12 and 6v. Rather than use wasteful linear regulators I put together some switching ones, using some free samples I snagged from National Semiconductor. These are way more efficient – essential for battery powered devices.

It takes a bit of maths to work out the right inductor and capacitor, but the output is lovely and smooth.

Switching power modules

I’ve got the speakers, light flashers, ring mod and processor added, along with the running lights…

Still a long way to go, but looking pretty good.

(I got the Dalek to sing “Happy Birthday” to my daughter and she started crying… So I guess the fear factor is about right?)

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Pete put together this pressurized static spark gap – the results are some of the best we’ve seen so far.

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This footage shows the advantage of having a phase controller for the synchronous motor. Using the dial we can alter the phase relationship of the motor until it dials in exactly with the up and down swing of the AC supply.

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