Need a bigger brain! Question about LT1054

[armdnrdy]

In an earlier reply I asked what size filter caps you were using. You replied "As for filter caps, I am using the generic values according to the voltage doubler circuit on the datasheet for the LT1054 Sheet 10"

I use BFC! The data sheet states small caps (cheaper, less board space = production friendly) but 99% of the time I would bet that the LT1054 or any other model of charge pump is not being used in an audio circuit.

I use 100 to 220µf filter caps. Think of it as a.....well...power supply!

For CIN across pins 1 & 4, I also use a larger cap than the specified 10µf.

If none of the above fixes the problem....I think it might be an issue with the "sewer ground" ( to quote R.G.) getting mixed in with the signal ground.

[Govmnt_Lacky]

In an earlier reply I asked what size filter caps you were using. You replied "As for filter caps, I am using the generic values according to the voltage doubler circuit on the datasheet for the LT1054 Sheet 10"

I use BFC! The data sheet states small caps (cheaper, less board space = production friendly) but 99% of the time I would bet that the LT1054 or any other model of charge pump is not being used in an audio circuit.

I use 100 to 220µf filter caps. Think of it as a.....well...power supply!

For CIN across pins 1 & 4, I also use a larger cap than the specified 10µf.

If none of the above fixes the problem....I think it might be an issue with the "sewer ground" ( to quote R.G.) getting mixed in with the signal ground.

@Larry

I used 470uF from the 9V input to the LT1054 and I used 220uF for the Vout before the regulator. I DID NOT try altering the CIN cap though. Every voltage doubler config that I have seen has always used 10uF there  

As far as the "sewer ground" goes. I isolated the grounds from the charge pump portion of the circuit and ran them in parallel with the signal grounds to the DC jack. Still no change in the noise.

@chrome

If you find a way to get it to Shhhhhhhhhh. Please let us know!  

[moosapotamus]

> a 9V to 12V charge pump

Charge-pumps are really, IMHO, best used "no"-load. Substrate bias, static CMOS, etc.

Yes they can power small chips.

But there are more serious approaches.

http://www.pololu.com/catalog/product/799

True, it's $12, but you've spent that much time already.

And it can approach 1 AMP out for 9V in 12V out, far beyond any $1 pump.

This looks the bomb! For sure, you could DIY for a lot less than $12, right? Any idea what the schematic looks like?

~ Charlie

[Govmnt_Lacky]

This looks the bomb! For sure, you could DIY for a lot less than $12, right? Any idea what the schematic looks like?

I agree Charlie however, after you invest the time and energy in gathering the materials and reversing the layout.... you are way past $12 into it.

This would be an outstanding idea for a Group buy however, it is not allowed here 

If you got 50 of them it would be down to $10/ea.

[armdnrdy]

This power supply can be made with through hole parts for next to nothing! I believe that the DIP-8 converter IC is the MC33063. You can find these IC's for as little as .45 cents.
If you look at the components on the board in the link, you'll see that it looks very similar.

http://www.e-gizmo.com/KIT/NEGATIVE%20DC%20DC.html


I've had parts waiting in a box to breadboard a power supply based on the MC33063 for a Bi-Phase build.

Check out the data sheet for the MC33063, try to bread board a supply and see if it "plays nice" with your build.

[moosapotamus]

Well, rather than reversing it, I was thinking that someone here might already have a pretty good idea of what's going on with it. At the same time, I might try reading up on switched-mode power supplies, myself, for fun.

~ Charlie

[moosapotamus]

This power supply can be made with through hole parts for next to nothing!

... and, there we go. Thanks, Larry!

~ Charlie

[moosapotamus]

Finally had some time to start following up on this...

I can confirm that the boost/regulator that PRR pointed to works!

http://www.pololu.com/catalog/product/799

Thanks, PRR!

IOW, it silences the "short wave radio like" noises that occur in the low freq range of the sweep in my MN3007 ADA flanger clone when powering it with a 9VDC wall wart and the onboard LT1054 voltage multiplier. I'll bet it would also do the trick to solve the similar noise issues that people have mentioned having with other flanger circuits, too.

This seems like a pretty slick little DC-DC converter circuit to me (but, then, I don't get out much). It's only a little bit bigger than the single-chip solutions that are available from Traco, Murata, etc... and it costs a lot less, and handles a lot more current! But it would still be nice to come up with a DIY solution for this.

I can't tell what converter chip is in the Pololu circuit. looks like a dip-10 smd package printed with the following...
4501
1120
G920

There also appears to be a diode with the following marking...
33
M17

Anyway, the MC33063 mentioned by armdnrdy does look like it would do the same thing, but I'm still trying to figure out how to adjust the output.

LM2577 also looks like a good candidate. Need to do some more research...

~ Charlie

[armdnrdy]

Hey Charlie,

The  MC33063 is kind of "old" technology. There have been many improvements based on this design. I don't have any part numbers offhand so you'll have to look around on the net.

The MC33063 being "old" technology has quite a bit of support available on the net including a design tool that allows you to calculate  component values.

http://www.nomad.ee/micros/mc34063a/

I been busy with other projects and still haven't bread boarded the MC33063 bipolar supply. Will report results when I do.

[moosapotamus]

Thanks for that link, Larry.

FWIW, I believe the Pololu circuit uses a SC4501 (available from DigiKey). Looks like another good option.

~ Charlie

[armdnrdy]

Hey Charlie,

There are so many DC to DC converters! It just clouds the issue when trying to choose one for an application!

I took a look at the SC4501. It has a couple downsides for my use. It's not through hole, (not that I'm afraid of SMT) It's a step up converter, (I run a DC brick that has 18 volt and 9 volt outputs so I usually start at 18 and step down) and for bipolar purposes, I didn't see an inverter application in the data sheet.

[moosapotamus]

That makes sense, Larry.

The application that I'm interested in is the same as Govmnt_Lacky and others - powering a modulation effect, like a flanger, that requires an internal voltage of 15V from a standard 9v pedal supply or wall wart. So step-up regulation is what I'm looking to do, for now. These DC-DC converters don't seem to have the noise problems that charge pumps like MAX1044 and LT1054 can sometimes have.

I've been looking at a few different DC-DC converters. Yes, there are a lot of them out there, and some are even more expensive than that Pololu PCBA. So I keep coming back to your original suggestion - MC33063. Seems to have the biggest bang for buck that I have found so far. I'll probably get a few to play around with.

Thanks
~ Charlie