Voltage doubling

[Happy Jack]

I recently read on another topic that you can use a voltage doubler to convert 9V DC to 18V DC, allowing some power-hungry pedals to run off a standard power supply.

I currently use a single plug with multiple 9V DC plugs daisy-chained off it (can't remember the make), so a simple way to use that with more demanding pedals would be very welcome.

I looked up voltage doubling on t'Net but what came back was a bunch of "simple DIY circuit boards", which is not at all what I'm after. Looking for "doubler" in the Maplins catalogue got me nowhere, too.

Two questions:

1. Where can I get a voltage doubler? The smaller & simpler, the better. Ideally, an adaptor into which I plug a standard BOSS-type 9V plug would be best.

2. If I use a voltage doubler to convert 9V to 18V, can I use that with a 15V pedal? Or will I fry something?

[obbm]

Jack, talk to Alien (Andy). He made one for me to fit to one of Higgies pedals a couple of years ago.

[escholl]

Assuming you don't need more than 30mA current draw, [url="http://www.diago.co.uk/component/page,shop.product_details/flypage,shop.flypage/product_id,39/category_id,3/manufacturer_id,0/option,com_virtuemart/Itemid,206/"]Diago has a solution.[/url]

Not in stock at the moment but probably worth asking them about it.

As for the 15V/18V thing, even though it's only 3 volts if may depend upon what IC's are used in the pedal. Ask the manufacturer? Some are more helpful than others.

[Happy Jack]

That Diago thing was pretty much what I had in mind, but they don't seem to have been available for a LONG time!

[Buzz]

Doubling voltage is basic electronics, however a bit of a pain with DC.

Normal principle of operation is to convert DC to AC in some way (an inverter will do the job), tranform the voltage up (transformer and/or use a voltage doubling circuit, lots around, dead simple), and then rectify it back to DC.

There are some other ways, and some off the shelf chips that do DC-DC.

The issue is current though. Doubling the voltage halves the current as Power has to remain constant (ref: Ohm's law / Joule's first).

But I'm certainly not that knowledgable in electronics, perhaps a pm to Dave Hall or Umph will set you down the right path.

[Happy Jack]

Yes, I was hoping to avoid actually having to [i][b]understand [/b][/i]anything.

I'm perfectly happy with a black box solution. Some sort of magic happens inside, and I get what I want.

[Al Heeley]

It would be pretty cheap and simple for someone to put something like this together on veroboard and put it in a little enclosure.
Drop me a pm if interested I can price it up for you.

[Alien]

[quote name='obbm' post='851019' date='May 29 2010, 12:10 PM']Jack, talk to Alien (Andy). He made one for me to fit to one of Higgies pedals a couple of years ago.[/quote]

Thanks for the shout out Dave, but as I recall it was never really quiet enough was it?

I seem to recall a conversation with Higgie about how to reduce the noise, but it was a while ago, and I don't think we ever came to a satisfactory conclusion.

A

[flyfisher]

[quote name='Happy Jack' post='851530' date='May 29 2010, 11:57 PM']Yes, I was hoping to avoid actually having to [i][b]understand [/b][/i]anything.

I'm perfectly happy with a black box solution. Some sort of magic happens inside, and I get what I want. [/quote]
All things (well, most things) are possible but since such a DC-DC converter will be a separate unit anyway (although that Diego unit looked neat), I think I'd just use a separate 18V PSU.

DC-DC converters generally use some sort of switching technique to increase the voltage and electrical noise can be a problem. It should be relatively easy to filter this out, especially as we're only talking about audio frequencies here, but it all adds to the cost. Also, such devices are not exactly commonplace so prices will reflect the relatively small production volumes compared to a 'standard' 18V PSU.

As for using a higher voltage than specified, a lot will depend on how the device handles the input voltage in the first place. Many devices have their own internal voltage regulators to provide a lower but much 'smoother' voltage supply than is often provided by cheap PSUs. Such devices should be able to tolerate a slightly higher input voltage, but power dissipation can become the limiting factor, i.e. they'll get hotter than intended, which might cause them to fail (if they are poorly designed) or to shut down to protect themselves. neither is exactly ideal in a gigging situation!

All in all, I'd also be happy with a 'black box' solution . . . an 18V PSU.

[Happy Jack]

Thanks for all the help & advice above.

Given the lack of a simple, cheap, noise-free solution I am now investigating a different route ... I'll report back in a few days.