Post your Silicon Chip/Jaycar kit questions here!

Posted: 3/23/2005 7:25:18 PM
DrMoze

From: Noo Yawk Citay

Joined: 3/6/2005

Thought I'd start a new thread for Q's on the SC/Jaycar kit, and start it off with a question of my own!

Just got my kit, and although it'll be a while before I can devote time to it (finals and work in the way), one thing I couldn't figure out. What are the 9-10 small gold pins for? They are in th eparts list and in the clear bag, but I saw no reference to them in the assembly instructions. (I did not read every line of the article so it *could* be in there, but I didn't see any reference to them when I read it a while back either.)

Also does anyone know a good source (US) for a 7806 regulator (to replace the 7805 one)? I saw this recommendation a few times in my reading.

Thx!!
Posted: 3/23/2005 7:46:52 PM
DrMoze

From: Noo Yawk Citay

Joined: 3/6/2005

More Q's (forgot to add to my last post!):

Does the internal speaker switch off when the external jack (line out) is used? Or does it stay on even when playing through an external amplifier?

I also plan to hook my 'min up to a large powered PA amp (which I also use for keyboards and electronic drums). Can I just use a 1/4" jack instead of the supplied rca jack for the line out, or do I have to modify the output at all?

Has anyone else added external pots for the modifications (mostly Maxie's) to improve adjustability? I think this would be helpful for setting the null point, adjusting tone linearity, volume gain, etc. The Theremax and Kees 'mins seem to have a few extra external adjustments.

For those whio have adjusted and played a theremin, which controls are particularly handy to have external knobs for? I plan to make most of the trimpots in the Maxie mods as panelmount (or back-mount) pots.

Also, has anyone added a coil to linearize the pitch sensitivity as suggested by maxie? If so, approx. what size is it? (I know it varies with antenna diameter etc.) I was just wondering if one could use the calculator with a rough calculation to create an appropriate small couil of wire, and mount it inside the case between the circuit board and pitch antenna. Maxie's notes do not give much detail on this.

On the plus side, I do plan to document all of my mods to the Jaycar kit (incl. adding external pots and what each does, and a modified circuit layout), so that others can have a more detailed guide to modding their own kits in the future.
Posted: 3/24/2005 2:36:01 PM
Abdulkn

From: UK

Joined: 2/21/2005

The pins are to be used on the PCB in order to connect any leads leading away from the board. i/e. Speaker, Poser Switch, Line-Out connector, Aerials and power connector.

Not sure where you'd get a 7806 in the US, but the one I'm working on seems to work fine with the supplied 7805

Kind regs

Abdul
Posted: 3/24/2005 2:43:29 PM
Abdulkn

From: UK

Joined: 2/21/2005

The internal speaker does not switch off when the line-out is used. You could wire up a socket to do this for you though, or do what's on the Etherwave Pro, and install a panel mounted switch to switch off the speaker. Pay careful attention to the switch used on the Etherware Pro.. it has an LED on the shaft (Cool huh!!)

jacking directly into an amp from the line-out should work fine.

I'm writing an article for Jason at the moment chronicling my efforts in building and modifying this Theremin, so watch this space inthe next couple of weeks..

Stick with Max's reccomendations of which pots wi have palen mounted. (Pitch fine tuning and Volume oscilator fine tuning, and of course, the main volume!)

I'm still trying to work out the on-line calculator for the coil, so not yet sure on this one. Could do with Max's help here too..

Hope this helps..

Abdul
Posted: 3/24/2005 3:02:45 PM
Abdulkn

From: UK

Joined: 2/21/2005

Hi..Again..

Here is a US supplier for the 7806 reg..

http://www.eidusa.com/Electronics_Voltage_Regulator.htm


Abdul
Posted: 3/24/2005 3:04:08 PM
DrMoze

From: Noo Yawk Citay

Joined: 3/6/2005

That helps a lot! Seein as I am totally boked for the next week or 2, I might get to see your info before I get into my own project.

I was also thinking of panelmounting the 10k trimpot (subbing a regular pot) that is in Maxie's Sound mod (original mod), to vary the tonal quality. I figure this will give some external control for varying the mix of sine wave/sawtooth.

The switch for the internal speaker sounds like a good idea and easy. I can see some situations where it might be desirable to have both (using the internal speaker as a 'stage monitor').

Looking forward to more reports from you!!
Posted: 3/24/2005 5:43:09 PM
chuckbobuck

From: SF Bay Area

Joined: 3/24/2005

I built the Jaycar kit about a year ago. The pins your are refering to are to connect the potentiometer pins and housing to the PC board. As far as external tuning, you can adjust the theremin using the antenna that it comes with. Just shorten the antenna a few inches, tune the circuit, and then adjust the length to zero it out. Very simple. If you want to make all of the mods, more power to you. If you build the kit in the basic configuration at least you can base-line your changes.
Posted: 3/25/2005 7:41:46 AM
MikeO

From: Italy

Joined: 2/19/2005

DrMoze I have some photo to show you concerning the silicon chip modified theremin.
I am following the maxis modifications plus I added something more:
- red led which light on when the theremin is switched on
- headphone support (same pins of loud speaker)
- battery support (same pins of power supply)

I am mounting on the pannell just 3 pots: Fine tuning volume, fine tuning pitch and main volume

Email me at michelangelo79@libero.it so I can send you some photo about the modified pcb and the wooden case too!

See ya
Posted: 3/25/2005 8:07:05 AM
Jason

From: Sammamish, Washington

Joined: 2/13/2005

MikeO, if you'd like, I'd be happy to host those photos on Theremin World & link them to the Jaycar theremin page. Or, if you already have them on the web, let me know and I'll link to your site.
Posted: 3/25/2005 7:26:05 PM
MikeO

From: Italy

Joined: 2/19/2005

Ok, I have sent all the pics of my SCmod theremin in construction to jason (using the submit@thereminworld.com address)

I hope to find soon a link to my pics in the bottom of SCmod page in schematic section! :)

I didn't wrote down anything yet, somebody says "an image worths more than 1000 words" ... I hope that's true even with theremins!

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