Advice required for analog drum synth.

[pizzatime]

Hi,
I'm really new to electronics and such but have jumped in a few steps further down the road then I probably should of and bought a QuadBass++ analog drum synth PCB off electro-music.com. I've got music studio kit but none of it is DIY but want to start using analog DIY bits and pieces..
Have soldered a simple synth kit previously.
My question is ( and it would be much appreciated if someone could give me some advice as I'm going round in circles reading up on the net) about the power supply.
I thought I could just build this thing up as it's bought as a kit with all the bits but I've found out it runs off a dual regulated + / - 15v supply of which nothing is really mentioned. Was then recommended a kit from America for about $40 but I'm in the UK so that's not ideal and I'm too inexperienced to mess about with 240v into this thing I and there's big warnings on the site saying 'DANGER! - experienced builders only kit!' etc as expected.
Pre built ones seem really expensive.
Someone has altered certain parts of his QuadBass++ to run off 2 x 9v batteries and he says this would give me up to 10 hours of use.. sounds good but this would cost me a fortune in batteries the way I work..
Is it possible to cheaply build a + / - supply kit but then power it from a bought cheapo adaptor so I'm not actually using mains power just the adapters output of 9v or whatever?

Was told also it is pretty complicated to convert a dual + / - supply PCB to normal supply but I found mention of someone suggesting a TLE2426 rail splitter.
Any advice on whether I should just run off batteries, pay someone to make a + / - supply kit for me or whether it is even possible to use a standard supply with this rail splitter would be great.. I should say this module will ideally be portable in its own case so a big lump home made supply wasn't something I ideally dreamt of..
If anyone can be bothered reading through all this it would be great to have any suggestions.. thanks.

 

[canadaelk]

Use 2 wallwarts, or one wallwart and a DC to DC converter with +/-15VDC out (V-Infinity series VESD1 or VESD2). E

 

[pizzatime]

Hey man,
Thanks for the suggestion.. will look into that now.
I was slightly embarrassed because I read a few more other posts after I posted and how technical they were and I sound like a numbskull!
I do have analog synths that use standard supplies so I assume this dual supply is to make it compatible with a modular synth.
I can't find anywhere why a dual supply is used at all though.. I assume to make the circuit much simpler somehow or to supply a proper constant non fluctuating supply.. Got to start somewhere with this though so cheers again.

 

[pizzatime]

So if I got my head round this and when I know what I'm doing it is possible to use any 15v normal wall-wart supply and then that goes into a small $8-ish DC/DC converter (somehow...oh dear) and I could just mount that inside the synth box. Will read up further now I have a lead to follow.. Thanks - I'm not overly concerned with the technical aspect at the minute and I wasn't wanting someone to do the work for me but as long as I know what is possible I can start reading up.

 

[canadaelk]

pt:
The reason for +/- supply is the way analog ICs work. With a "split" power supply the inputs and the output of an op-amp are at (or very close to) ground or common (centre of the +/- supply), which generally is the reference point of a circuit, making the circuit design much simpler than a single supply, where you have to create an artificial (virtual) ground.
Now my head hurts (again).
Cheers, E

 

[pizzatime]

Hi, thanks for your help again.
Could a 15 AC adaptor or (9) AC be used to give a +/- 15v or (9v ) Bipolar Supply or is that just not right and the suggested way is the best way? Cheers.

 

[pizzatime]

Right I will leave it after this and read up as I don't know what I'm talking about.. just seen a similar box and it is one AC 12v supply to do + / - bipolar supply it said but I can't find any info and no one has told me it was that easy so don't know.
If someone could confirm if it was a 9v supply whether a 'charge pump' is what I need to look into as easiest/ cheapest solution.. that's it with power supply questions!!!! Would be great if someone could clarify this for me.

 

[alec_t]

By my reckoning if the synth can run be run for 10hrs from 2 x PP3 batteries then it draws ~ 50mA.
Here's a schematic for a simple (non-regulated) +9V/-9V supply powered from a 15V AC wall-wart rated at ~100mA or more.

 

[pizzatime]

Hi,
I might have posted this twice but I really appreciate your help.
Will look into that properly tomorrow.
Cheers.

 

[Mr RB]

If it specifies +/-15v you may not get proper performance running from +/-9v, the analog synth may not reproduce the envelope or filter waveforms properly.

Since you can get 15v wall warts fro a few dollars each I think Canadaelk had the right idea; just buy two 15v wall warts.

 

[pizzatime]

Hi,
Thanks. Yes, I had thought of that problem with performance but my knowledge is lacking and it's hard to find out about certain things when you've never heard of them or don't know what the proper name is ( I am trying to start at the beginning with basic electronic books too now!) - someone gave me notes on changing certain parts of the circuit and he is running 2 x 9v batteries to overcome power supply issue but I would go through too many batteries that way so it wasn't ideal. The best solution I have found so far is the 'music-from-outer-space' AC wall wart to bipolar board.. This is mainly because I'm not comfortable wiring up the normal +/- linear supply that works off mains power as it could be a bit dangerous for me to be experimenting with 240v so this would allow me to use an AC wall-wart and wire up a board kit to output +/- 12v so I'm looking into if that would power a +/- 15v board.. May just try that kit anyway as would come in useful in the future.. The kit costs about $32 I think.. just trying to find out now if there is anything similar in the UK or ideally one that can output the required +/- 15v which would be perfect if that is possible from an AC wall wart.. I'm getting there slowly!.. Thanks again.

 

[pizzatime]

2 wall warts would be a last resort I think as I want to use the box live and it to be portable so not an ideal solution but as you say it does sound the easiest and probably the cheapest way but something a bit more refined would be nice.. Have about 10 wall warts in my studio.. another 2 for one little box... oh man! Cheers.