Jaycar/Silicon Chip troubleshooting part 2

Hi Thereminoob,

It is fine using 1N4006 diodes ... they just have higher reverse-voltage ratings than the 1N4001s.

Don

Cheers for that, thats a relief, i have done all the soldering apart from the diodes which i will now do shortly. The only other problem i have is connecting the 10k pot, i have the 10 gold pins, but havent the foggiest how that connects the pot. Whats the easiest way to connect the pot to the board?

Hi all

Pins option 1

Turn the PCB over, put the pins through the hole and solder them.
Disadvantage is that you will have to solder wires to the other side and if you apply too much heat they will drop outbut its easiest.

so

Otion 2
Put the pins in from the top, shorter end down, find some way of turning the board over without them dropping out and solder.
Advantage is when you attach the wires the pins they won't drop out but they will get hot as you solder them and you'll have to use something that won't be damage or make a mess on the board.

Hope that helps

Regards

MarkT

Went with your option 1 method, did you use the wires given with the kit to connect the pot?

I did initially use the wire that came with the kit but as I have now installed it in a clear perspex case I used clear wire too but its only wire and nearly anything will do the job.

The really good thing about these kits is that they include everything you need, even solder.

Once you've built it and got it working, you'll be modding it! There's loads of info about this, but get it going first.

Regards

MarkT

Hi

Good news - I've just been given a Jaycar Theremin. Bad news, it doesn't work. I don't have access to any of the diagrams or instructions that it might have had with it and I am not sure if it is a home built job or a factory constructed model (any clues?) I'd like to get it running, but since my last experience with electronics was about 30 years ago, I'm a bit rusty. Can anyone help with circuit diagrams/construction details/instructions as a starter and we'll take it from there.

There are circuits diagrams etc on Max's famous mods page:

http://www.thereminworld.com/
silicon_chip_theremin_modifications.html

Get it working first before you do the mods!
What are the symptons you are getting at the moment?


MarkT

Newbie Theremin constructor here, just finished soldering up a Jaycar kit and it all seems to be working pretty much as advertised. I do seem to have one issue though - the pitch control doesn't seem particularly "sensitive" if that's the right word. I only get pitch variation when my hand is relatively close to the aerial, perhaps under 5 or 6 inches or so - is that normal? If not, where would I be best to start looking for the issue? The volume control seems more sensitive to me, which probably shouldn't be the case.

I'm also finding tuning T2 to be incredibly difficult (that may be why I haven't found the "sweet spot" that will give me sensitivity). Any tips for how to make that easier - would tweaking T1 help?

Thanks in advance folks!

Hello AngusR,

The pitch on my Jaycar is quite compressed towards the antenna and the scale is quite unlinear. The bass notes are "compressed" and the treble notes are very spaced. I've tuned mine per the instructions that Jaycar provided - but as noted elsewhere - it is the opposite to most Theremins that have the treble notes towards the aerial and the bass notes furthest away.

I certainly get a much larger range than 5-6 inches though - however the easily usable pitch range might be somewhere in that order.

Personaly I'm going to apply the mods on Max's page as mentioned earlier in this thread - I believe some of the modes may help with the linearity issues - in particular the inductance coil in series with the pitch antenna.

Hope the above assists and best of luck with the project.

Are you using the telescopic aerial as the pitch control? Unless you have it exactly the same length every time, you will have trouble tuning it.

As you've got past the first stage and got it making sound, the next step is to put it into a bigger case with a fixed length pitch control rod. This makes all the difference to these kits and is the best first mod to do.

Then, you can look at which of Maxies mods you want to do.
But, really, put it into a bigger case with new rods first as this gives you a constant to work with and makes things so much easier.

Any problems, please post back.

MarkT