Author Topic: Maxx1044 negative voltage inverter  (Read 359 times)

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Guurf2

Maxx1044 negative voltage inverter
« on: December 24, 2017, 12:05:09 PM »
Hi

so i tried breadboarding a 9v negative voltage inverter of a maxx1044 chip bought of ebay from china.
used this schematic: https://www.abcelectronique.com/annuaire/montages/cache/348/tension-symetrique-a-partir-d-une-batterie.html

it works, the chip doesn't heat up but problem is, it delivers only 7V negative voltage and not 9V as it's supposed to.

anybody had experience with these? can someone help me?

Thanks!

Guy F.

Aph

Re: Maxx1044 negative voltage inverter
« Reply #1 on: December 24, 2017, 10:48:28 PM »
I'm using one in a circuit and get a .15 voltage drop when it's powering nothing. When I add the two RC4558 opamps it powers, I get a 1.3 voltage drop (the circuit works fine).
You could try an LT1054. I think it can supply more current.

Guurf2

Re: Maxx1044 negative voltage inverter
« Reply #2 on: December 26, 2017, 05:22:34 AM »
Cool thanks!
How about the ne555 or icl7760?
Do you think any of them would do better?

Aph

Re: Maxx1044 negative voltage inverter
« Reply #3 on: December 26, 2017, 07:56:04 PM »
(I think you meant ICL7660...)
Someone with more experience with charge pumps will have to chime in, but I doubt if either would work better, especially the 555.
Also, you can get the LT1054 from different manufacturers. I know the specs are supposed to be the same but you could try one from Texas Instruments and then Linear Technology. I've always planned to do that... haven't gotten around to ordering a few to try.

Guurf2

Re: Maxx1044 negative voltage inverter
« Reply #4 on: January 03, 2018, 11:48:43 AM »
(I think you meant ICL7660...)
Someone with more experience with charge pumps will have to chime in, but I doubt if either would work better, especially the 555.
Also, you can get the LT1054 from different manufacturers. I know the specs are supposed to be the same but you could try one from Texas Instruments and then Linear Technology. I've always planned to do that... haven't gotten around to ordering a few to try.

Thanks!
Yeah i meant 7660 Lol.
So i'll check out the LT1054.
anyway,
anyone with more experience with charge pumps would like to help me out here?
Thanks,

Guy F.

Aph

Re: Maxx1044 negative voltage inverter
« Reply #5 on: January 03, 2018, 03:59:52 PM »
One more thing... PRR reminded me about using low ESR filter caps in these designs... like tantalums, etc.

garcho

Re: Maxx1044 negative voltage inverter
« Reply #6 on: January 03, 2018, 04:06:05 PM »
Just curious, do you want to have bipolar DC, as in +9 and -9 at the same time? Or are you looking to power something with "positive ground" like a fuzz face or something? If you want bipolar, i'd buy an AC to 12VAC wall wart adapter, power diodes, some big caps and L7809/7909 or LM317/337.
The output voltage of the 1044 is unregulated, so current would cause that to fluctuate, like Aph was saying. The MAX1044 datasheet states it drops half a volt with 10mA. You'll want to figure out how much current you need and then check out some datasheets.
I would also try buying a couple from a reputable seller, not nearly as many fakes out there as people want to believe but they do exist, especially from faceless, nameless ebay sellers in a far away land...
EDIT: are you testing this with a load?
« Last Edit: January 03, 2018, 04:07:59 PM by garcho »
"...and weird on top!"

EBK

Re: Maxx1044 negative voltage inverter
« Reply #7 on: January 03, 2018, 08:28:40 PM »
I'll throw in a question:
Have you measured your input voltage?
No affiliations. If I glowingly mention specific merchants or products, it is because I like them without having to be paid to like them.

Guurf2

Re: Maxx1044 negative voltage inverter
« Reply #8 on: January 04, 2018, 07:07:56 AM »
I'll throw in a question:
Have you measured your input voltage?

Yeah, it showed 9v.

Just curious, do you want to have bipolar DC, as in +9 and -9 at the same time? Or are you looking to power something with "positive ground" like a fuzz face or something? If you want bipolar, i'd buy an AC to 12VAC wall wart adapter, power diodes, some big caps and L7809/7909 or LM317/337.
The output voltage of the 1044 is unregulated, so current would cause that to fluctuate, like Aph was saying. The MAX1044 datasheet states it drops half a volt with 10mA. You'll want to figure out how much current you need and then check out some datasheets.
I would also try buying a couple from a reputable seller, not nearly as many fakes out there as people want to believe but they do exist, especially from faceless, nameless ebay sellers in a far away land...
EDIT: are you testing this with a load?

1. i wanted to made some module with these maxx1044s to stick in each of my positive ground pedals. also another thought i had was to make a section of inverted negative voltage for a power supply i'm building, but all these inverter chips give an output current which is too low...
2. actually i tested without a load, i later read that a lack of load might have actually been the reason for the big drop.


anyway there is something i need to understand about the whole concept of positive ground.
well up until today i knew it as a fact - circuits with pnp transistors have a positive ground.
than i saw some "solutions": voltage inverters, re-designs with negative ground And pnp transistors, and so on. for example i looked inside a friend's Jext Telez Rangelord Gold (it has an OC44 pnp transistor in it) and there is no inverter in it, just a plain normal circuit and somehow it works, daisy chained to some other negative ground pedals.
So - what's the "Rule of the thumb" here? how do you make a pnp transistor based circuit work with a negative ground? when do you need an inverter? do you even need it at all? are all the inverter-less circuits with pnp and negative ground just a case of a lucky "hit and miss"?

Thanks a lot again!

Guy.


R.G.

Re: Maxx1044 negative voltage inverter
« Reply #9 on: January 04, 2018, 10:06:28 AM »
One caution about the MAX1044: it dies at input voltages greater than 10.000000V.

The output voltage of a fresh alkaline "9V" battery is in the range of 9.4-9.6V, so there's precious little headroom for little spikes and transients. External AD>DC power adapters, especially home brewed ones and unregulated ones may hit more than 10V for short times and kill the chip. At least one commercial pedal had exactly this problem.

It's a good idea to use an alternative chip for pedals powered by 9V, one that is rated for an absolute max voltage of more than 10.0V.
R.G.

Quick IQ Test: If anyone in a governmental position suspected that YOU had top-secret information on YOUR computer, how many minutes would you remain outside a jail cell?

rankot

Re: Maxx1044 negative voltage inverter
« Reply #10 on: January 04, 2018, 11:48:17 AM »
LTC1054 is much better than LT1044.  8)
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garcho

Re: Maxx1044 negative voltage inverter
« Reply #11 on: January 04, 2018, 12:31:15 PM »
Quote
So - what's the "Rule of the thumb" here? how do you make a pnp transistor based circuit work with a negative ground? when do you need an inverter? do you even need it at all? are all the inverter-less circuits with pnp and negative ground just a case of a lucky "hit and miss"?

lucky for you, that's what we like:

https://duckduckgo.com/?q=how+to+make+positive+ground+negative+PNP+site%3Adiystompboxes.com&t=ffab&ia=web
"...and weird on top!"