Charge pump for +15v/-15v?

[jubal81]

I think it's fine without 'em but I'm not an expert on that.
Here's a snip I like from the AION Korg preamp project:

[midwayfair]

I think it's fine without 'em but I'm not an expert on that.
Here's a snip I like from the AION Korg preamp project:

wow, that's all that's involved?

How big is the converter itself? About the size of a chip? I'm rethinking a certain 15V project now ...

[rullywowr]

It's small. Like sip7 but only uses 5 pins. 6mm x 19mm (I just drew a DipTrace footprint so it's on the top of my head)

[jkokura]

That method seems much more efficient. What's the link for the Murata's price and datasheet?

Jacob

[rullywowr]

That method seems much more efficient. What's the link for the Murata's price and datasheet?

Jacob

I've seen this device used in other circuits, both DIY and commercial....a little pricey but is a slick trick.

http://www.mouser.com/ProductDetail/Murata/NMA0515SC/?qs=%2fha2pyFaduhFiAPVWrTrFQM2YxeR6Wl2ZuHmK8xFWK4%3d

[RobA]

Depending on how much current you need, check out the RECOM parts as well (RB-0515D). I think they are cheaper at mouser, around $5.50(US).

I've been playing with them and they are good. The only problem I've had with going this way is that the linear regulator is pretty inefficient, and since the circuit I was working on draws more current at 5V than it does at the effect voltage, the wasted current was too high. So, I tried it with a buck converter to drop the 9V to 5V and then go up from there using the RECOM part. I ended up with the dreaded clock clash. I think if you were using less current and could afford the loses of using the linear 5V regulator that this is a better path than the charge pump. The RECOM parts are small and self contained and isolated. When I use them with a 5V input supply, they provide really clean power.

[jkokura]

Yeah, at $10 I'm not sure about it as much.

Jacob

[rullywowr]

Depending on how much current you need, check out the RECOM parts as well (RB-0515D). I think they are cheaper at mouser, around $5.50(US).

I've been playing with them and they are good. The only problem I've had with going this way is that the linear regulator is pretty inefficient, and since the circuit I was working on draws more current at 5V than it does at the effect voltage, the wasted current was too high. So, I tried it with a buck converter to drop the 9V to 5V and then go up from there using the RECOM part. I ended up with the dreaded clock clash. I think if you were using less current and could afford the loses of using the linear 5V regulator that this is a better path than the charge pump. The RECOM parts are small and self contained and isolated. When I use them with a 5V input supply, they provide really clean power.

Rob, thanks for sharing this.  At 1/2 price it does look promising..and has the same pinout as the Murata piece.   

[derevaun]

This all seems like a lot of trouble and power dissipation to go to when you're not going to actually use a battery anyway. How important is it to start with 9v? What about just setting up a +-15v source along with the 9v? I don't know which option would be better even for my purposes, but they seem pretty close in terms of return on effort.

[rullywowr]

This all seems like a lot of trouble and power dissipation to go to when you're not going to actually use a battery anyway. How important is it to start with 9v? What about just setting up a +-15v source along with the 9v? I don't know which option would be better even for my purposes, but they seem pretty close in terms of return on effort.

It's really for those circuits which were designed for it.  Many preamps and the like use this scheme. The added voltage swing creates a lot more headroom. These of course are not going to be powered off a 9v battery but rather a power supply when incorporating into a pedal format.

[derevaun]

Right, so it seems like making a dedicated bipolar supply, back at the AC adapter stage, could be a good idea, rather than doing all the conversion in the box with the high impedance audio signals. But I can see how it would be a barrier to selling/building for others, etc.

[rullywowr]

Right, so it seems like making a dedicated bipolar supply, back at the AC adapter stage, could be a good idea, rather than doing all the conversion in the box with the high impedance audio signals. But I can see how it would be a barrier to selling/building for others, etc.

Exactly. Dedicated wall warts are a pain to deal with, ensure they are the correct one, keep with the pedal etc.

[Scruffie]

An LM317 set to 7.5V and a Bipolar TC1044 Doubler?

[aion]

A little late to the discussion, but I wanted to add my perspective from doing the SDD Preamp board that was referenced earlier. I didn't do the math on the current draw, so I initially tried to use a 78L05 regulator (TO-92). It got very, very hot. And the SDD preamp circuit is just two op amps, so the base current draw at 9 volts is not a lot more than an overdrive. Anyway, I ended up using a full-size 7805 instead and it worked out great - but the lesson was, don't underestimate the multiplicative effects on current draw when going to 15V bipolar if you're accustomed to working within 9V single rail supplies.

[rullywowr]

A little late to the discussion, but I wanted to add my perspective from doing the SDD Preamp board that was referenced earlier. I didn't do the math on the current draw, so I initially tried to use a 78L05 regulator (TO-92). It got very, very hot. And the SDD preamp circuit is just two op amps, so the base current draw at 9 volts is not a lot more than an overdrive. Anyway, I ended up using a full-size 7805 instead and it worked out great - but the lesson was, don't underestimate the multiplicative effects on current draw when going to 15V bipolar if you're accustomed to working within 9V single rail supplies.

That's sound information, thanks.  In your experience, you feel the inductors aren't required with the Murata?  Just wondering what would be the worst case scenario of not using them, or if there are any drawbacks?