Month: August 2009

Isn’t serendipity a fine thing? I found these little tins for mini teddies today on one of my sally anne and mountain top climbing forays.

Mountain climbing forays you ask? Indeed! I’m thinking about doing a bunch of really big paintings of the old dead volcano cones of Auckland city… with a metaphorical twist, and today I climbed to the top of two discrete little rises that don’t even have proper names as such but happen to be in the middle of parks. The first one I can’t remember the name of but it right at the southern end of Dominoin Rd and right next to the new motorway and the other is the remaining King of the three kings and so called Kings reserve. On that one I bet a fellow I could climb the anti climbing stuff andd get on the top of the resrvior but he declined saying he didn’t want to see me fall and have to run down the hill to call the emergency services. So when he was out of site I climbed it anyways, even though he didn’t take up the bet I was going to make him for twenty bucks, but kinda scared myself when during the trickiest bit my arms went a bit jelly on me and it looked a long way down. I survived and made it to the top and was so rewarded with an absolutely magnificent view and when I looked over the side. There he was, down the path, waving up at me.

Aren’t those little tins just gorgeous? Bit girly I know but absolutly of the right design to put little circuits into with the minimum of fuss. I’ve never seen a match box style tin before and realised as soon as I saw them they were exactly what I needed. The circuit board and batteries can sit inside the box and have plugs on either end then the whole lot slides into the top and sides then the top can have a small hole in it to let the light shine on the LDR. Wonderful life isn’t it?, when everything you need appears jus after you’ve forgotten you needed it.
I think I’ll use this schematic and get the really big LDR’s from surplustronics… they have under the counter. I wonder why these people cal them cds photocells?

It’s not really my kind of website. Interesting stuff but not enough diehard info about how the stuff works. But I haven’t really had a good look about and it might be in there somewhere… but I absolutely love the aesthetic!
Get Lofi.com
And isn’t this poster just absolutely wonderful?

Now I’ve just got to find a webpage that allows me to convert my Mira into a time machine that can negotiate vast geographical distances and go back in time and accross the world to the garage sale of the lost and eternally special!

Quick little post here. Friend Felix sent me a link to a guy called Moldover who built an optical theremin into the jewel case of his latest CD so I went looking for optical theremins this morning. Well, I didn’t want to be so obvious so I went looking for light theremins.
First one I got I fell in love with and I’m thinking about doing something called the paper bag circuits. Long story but simply put I had a bunch of the kind of paper bags you get pies in, new and un-used, and when findin’ small circuits that didn’t require an A4 I picked up these paper bags. The first one was a speaker as a microphone circuit and this one is an optical theremin. Basically they are small and simple circuits where the schematic, parts list, and the working out of the etching for the PCB can all be done on one side of a paper bag. Whats come to mind is that I could build these little knee jerk reactions to over-complexity and mount them in eclipse mints cans and berocca tubes, have a number series thing going on, and sell them as artworks on Trade Me.

Complete, of course, with the original hand drawn paper bag.
The simplest little light theremin.

Okay, I haven’t done the TV yet. I’m waiting on getting some more bulldog leads so I can isolate the switching to just have the TV on but also remove the radio and tape cassette. Originally I wanted them all on at once but wiring it up so they are all on is beyond me so I’m just going to use the Cathode Ray tube and put it in another framework… somewht like the screens in the movie Brazil.

So I’ve finally gotten around to a few things not the least of which was hooking up the boss pedals and spending a bit of time with them. I’ve got a DD-7 digi delay and the RC-2 looper and the possibilities are nearly endless but it’ll be a while before I get my head around them. You know, read the manual as much as you can, even though none of it makes much sense, then go play with the thing for a while then back to the manual where it starts to make more sense… and on it goes.

As for setting up the recording… it doesn’t work on one channel so I’ll have to go through the mixer and figure out where but I’ve an idea and it should be simple enough to fix. Other than that I’ve got to do a switch block on the outs from the PC so I can switch in a simple amp when using the PC for browsing and stuff because otherwise it’s a hassle to switch mixers and amps and the whole caboodle on and off each time… and who needs a valve amp for U-tube clips?

So what I have for you today is the toy thing. In-organic is on again and I picked up a few more battery powered audio toys. Last year I tried sequencing them up but was having problems making them switch as the little toys work on pulsed DC and if you use a transistor to switch them the base voltage interferes with the pulsing DC accross the collector and emitter. I eventually realised, or was told, that the mosfets in a 4066 would do the trick where the control voltage, on the gate, is not interfering with the connection between drain and source. Last year I’d built the sequencer but it didn’t work with the toys so I used it on a drum machine… that kinda works but even that needs work. In the interim I learnt more about 555’s, more than one ever wants to, but now I pretty much have them sussed so I’m having another go at the toy thing.
Shit, I can’t copy and paste the pictures for some reason, they copy but won’t paste into this page… bugger. I’ll restart later and come back to this.
I can do normal copy and paste from here into the address bar so it must be the photbucket site. I couldn’t get the old uploader going until I un-installed flash so maybe something else in there site is fucking me up.

There you go… it works if I open the picture file on its own page then copy the link. Bloody internet. It’s becoming like you bloody need to be a techie.
Anyways above is the schematic. Top left is the power supplies for the toys which run on 3V and 4.5V DC and you can’t get regulators for that voltage easily so I’ve used a dual opamp to divide off the voltages and buffer them out at a low impedance. It’s what we do with a spare opamp section to create the bias for them working as signal amps but it works just as well for a regulated voltage. They should also have a cap, 22-200uf, sitting on the voltage divider from the divided voltage to ground.
Below that is the 555 which is kinda normal except for the 1N914 diode across pins 6 and 7. This shortens the on time and makes it constant so the off times are what changes. The toys just need a quick jolt to get them firing so maybe the 10k from he power rail could be lessened to about 1k or so which’ll quicken it right up. So the diode allows the cap to ground, off pins 6 and 2, to charge up as fast as it can with an almost direct voltage but then it discharges normally through the pot and this sets the off time. Actually there is an amount of time that caps take to charge that is dependant on the size of it so maybe I’m better going to a 4.7uf and a 10 uf and raising the pot to 500k.
So the thng fires off through pin 3 and that goes to the clock of the 4022 which basically cycles that pulse through 8 outputs. The outputs goes to the control inputs of the 4066’s and each time a pulse reaches a control the contacts go from a super high resistance, 100’s of megs, down to almost nothing, a few hundred ohms, so effectively become a switch closed.
To the far right and bottom is a diagram of the mixer to take all the signals from the toys and mix them all to one out. The thing is that these little toys actually use a bridged output which means the signal is divided between two amps, one does the positive swings and the other does the negative swings, from the bias point, and these are combined in the speaker from the 2 outs. What this means is there isn’t a positive out and a ground so I thought about it and realised I could put a voltage divider between the two amp outs and then take the signal from the middle, chuck it through a cap to take out that pesky bias voltage then into regular summing resistors. I tried it and it works. If I discover that one of the toys isn’t bridged I’ll simply go through 1 10k for the hot.

Heres as far as I’ve got. Two etched PCB’s that suffered somewhat in the etching process but theres enough copper to do the job. Saturday today and Monday night is when I want it to be playable.

The only other thing I’ll be doing is having the switch outs on the 4066’s wired up to RCA plugs then have the toys on 2 x 4 banks of RCA sockets. This way I’ll have a cheap patchboard to change the sequencer order or cut what I don’t want. It’s going to be absolutely nuts through fx… this cheap and nasty little sample player.

Bit bored today so as I was going through the experimentalists anonymous forums and I came across the “turn your old TV into an Oscilliscope thread” in the articles and tutorials section.

Basically it’s all there and you simply add a switch and an input to the TV and way you go. I’ve cut the wires and isolated the vertical ones and the horizontal ones but I’ve yet to determine the grounds. I’ll do that tomorrow. What I’ll do as well is isolate where the amp is and fix it so the signal in also goes to the amp so it really is sound and vision. The old TV I’m using was given to me by Blind Shaun and has a radio and a cassette player/recorder so I might have to do something iinteresting with them as well. The tuning for the radio is the old method of changing the capacitance in a tuned L/C amp so maybe I can get a filter of some sort together that will change the capacitance dependant on the signal in. Have to think about that one!

This is how to do it

As for the tape maybe I’ll be able to switch the play/record head and erase head wiring so I just have play and record and then just put a loop in the cassette.

I don’t think that normal guitar levels going to do it so getting it up to line level with a booster, what are they called when…thats it, followed by a buffer and maybe even a tranformer coupling for the input as there might be quite a bit of noise on the TV’s earth.

Have Fun… and be careful out there! (remember Hill St Blues?)

I went and got all the recording stuff outta the dusty corners where it’s been sitting un-used for the past few years, waiting for me to build a room for it, so I can get some of these instruments recorded. I haven’t tried it yet but no longer is it a matter of just plugging in the little bookshelf speakers. Now I have to turn on the mixer and then the amp and fiddle with settings on the soundcard.
Last time I used it I couldn’t play and record at the same time, which I know seems stupid, but thats what happened so hopefully this time I’ll be able to have it do what I want. I know it seems weird but the thing is that my mixer is designed to be used with the previous generation of this soundcard which means that the in’s and out’s for playing don’t mix with the in’s and outs for monitoring. I think people had problems with normal mixers which don’t have almost two mixers in one, one for sending to the PC and the other for return from the PC so they had feedback while mixing the send and return on the mixer bus. I solved it by designing my own mixer but it seems the soundcards changed to suit normal mixers… I’ll try and figure it out.

PC in a box to be sealed off from the world, with a fan and an air duct to another room, with a rack of stuff I don’t think I need anymore.

As for the insiders guide to happiness featured in the last post. I got another shock off the earths and finally realised it was the power supply I built and didn’t check. There was solder from the neutral to 0V on one of the transformers so when it was all plugged in it was safe but as soon as I pulled a lead out I’d get zapped from the voltage sitting on the neutral wire and then being on the earth. Stupid me huh! So I’ve replaced one PS cap that was round the wrong way, on the insiders guide to happiness, taken out a 6V max IC that was being fed 9V and replaced it with something that’ll work at 9V and turned another IC around that was in backwards and also changed out 4 transistors with some that are supposed to be in the particular circuit as opposed to ones I put in which won’t supposedly work… oh and corrected a circuit blunder on the same circuit. Bang, no wonder I got shocked making so many silly lazy mistakes.