9V to +-14v

[nickbungus]

Hi Guys

Sorry to bring this back up but we feel like we just haven't got this licked. 

I love the link from Larry(Armdnrdy) but, as we've had a lot of interest in this project, me and Aussie Nick are planning on making up a batch of boards and are worried that the smd will put off a lot of people.  It puts me off.  I ordered some smd chips and my wife nearly threw them in the bin because she reckoned rs components had delivered 2 empty bags.

I've been searching the internet to find a DIP equivalent to the LT3467.  I'm sure there must be something but I'm probably not searching correctly.  It would be nice to do it with one chip.

We've also been talking about using 2 chips and a regulator.
IC1 to double then using a regulator (like an LM317 to get 14v), then inverting for the -14v rail.

Or perhaps 2 chips and 2 regulators which might be better for the current draw.  IC1 doubles the 9v and then we regulate, IC2 doubles the 9v and inverts then we use negative voltage regulator for the -14v.

Any ideas will be more than welcome.  Board space is tight as its such a big circuit so the fewer components the better.  We've got something that works but are worried we are doing it like idiots!  

There is another option of making the boards with the smd chip already onboard but that brings in some logistical challenges.

[duck_arse]

have a look at the good old MC34063.

[nickbungus]

Thats excellent ducky.  Cheers buddy.

I take it I'll need to use 2 to get the +14 and the -14v or is there a way it can do both with one IC like the LT3467?

[nickbungus]

Hmm

I keep coming across this image (or variations) of it from places like here.



Only thing I'm not sure about is that transformer.  What is that?  A flyback converter apparently.  Dont know if its worth doing it that way or just use two MC34063s.

[rankot]

Why not using LT1054? Proven and small.

[nickbungus]

Sorry Ranko, thanks for your schematic.  I dont know why we have ignored it, I think I got a bit obsessed with the LT3467 alternative route.  We were also concerned about the max current from the LT1054.  From Aussie Nicks tests on his working clone the current on each rail seemed high.

I'll have a word with Nick and see if he fancies breadboarding your schematic.

[njkmonty]

I'm crook at present but will advise my results
Bipolar from lt1054 tested perfect until I connected to circuit the volts dropped too low +6. And -4v
However I've managed to just cram in a dual lt1054 with a to220 regulator and it just fits ( regulator mounted on pot side of board ) the dual surge pump idea worked perfectly in my clone circuit. And was as quiet as my 14vac transformer version

I have. No probs at all with two lt1054's. However I've just never seen anyone do it that way bedore
It's also. ISnt smd  And a common chip pedal makers source?!

[PRR]

The non-DIY path is DC-DC converter. Used to be used by the millions on Ethernet cards; also widely around telephony cards (all dead markets). Cost you 20 bucks, but may be cheaper than throwing-out bags of "pepper grains".

Digikey Search link {may not work for you}

RSO-1212DZ Recom Power CONV DC/DC 1W +/-12VOUT SIP $18.22
IP1212S XP Power DC/DC CONVERTER +/-12V 3W $19.95
ISU0205D12 XP Power DC DC CONVERTER +/-12V 2W $21.00
IEQ0512D12 XP Power 5W ISOLATED DC-DC CONVERTER, 4:1 $23.00
ISU0205D12 XP Power DC DC CONVERTER +/-12V 2W $25.00

Connections:

[rankot]

You can also try with this: https://www.aliexpress.com/item/dc-dc-converter-power-module-5v-step-up-to-positive-and-negative15v-dual-output-isolated-dc/1935768851.html

It is cheap (5 pcs for 12 USD) and convert 5V DC to ±15V DC. They can probably offer other options - 9V input for example, but it is not easy to search and find on this site. Drawback is that can supply only 67mA.

If you need more (200mA), try with this: https://www.aliexpress.com/item/2-1-wide-voltage-3w-0-2A-power-supply-module-12v-to-15v-dual-isolated-regulated/2027275014.html

[rankot]

Or you may try using XL6009, looks quite simple and works on 400kHz!

https://lib.chipdip.ru/164/DOC001164799.pdf

[NFX]

i told them about the dc dc converters but they didn't listen

[njkmonty]

i valued your input, however sourcing the right one with out having to spend $$ on a minimal order has been an issue,, i was trying to work around with common parts availble to me, and parts used frequently in diy community projects,, if that all fails then look down that road.

ive got it to work well and have enough room to fit it all on my board layout, I cant see whats wrong with using dual lt1054's?  Cost less than 14 - 20us dollars?
its just the part cost and the board size isnt going to change?

also if we end up getting a working project, we would like to make it  so parts used are as easier and cost effective in sourcing

this is sort of what we have so far....

the  6 diodes  in series are there with the option of jumpering them to get the desired voltage pending own tests

[NFX]

where will the 3 jacks go tho?

[njkmonty]

hows your layout going?    did you end up finding any bbd chips?

[amz-fx]

Looks like you need to ground the junction of C47 and C48.

Also, you should find out how much current the circuit will draw since charge pump voltages will sag significantly as you load it down. You might need to take this into account.

Best regards, Jack

[NFX]

Not started yet, I have 6 Panasonic MN3002s in my stash.

[njkmonty]

i tested my first one and from memory each rail was drawing between 30-60 ma
yes i saw that schem,atic correction   ive since corrected a few values etc and finished  , was just showing which way we went , however you have good eyes!


6 chips ! impressive

[DIY Bass]

These look like they would give you +-15 V at 100mA per rail, and it's through hole.  No idea of cost though

https://www.tracopower.com/products/tmr3wie.pdf

[njkmonty]

cheers, i like the look at all these power ic packages , but i cant ever seem to find anyone who sells them without having to spend of $100 on an order!

https://au.mouser.com/ProductDetail/TRACO-Power/TMR-3-1223WIE/?qs=ckJk83FOD0VpG70EJMzayg==

$24 !


i found some other ones on there that looked good but only handle +-33ma   and were under $4

https://au.mouser.com/productdetail/mean-well/dpu01m-15?qs=sGAEpiMZZMvGsmoEFRKS8Koqt8Pjkl39mGzvujnWEEkR3klXv%2Fo9dg%3D%3D

i think i might stay with the dual lt1054   ($3 each) and i use them in builds regularly) however i have one more single lt1054 layout to try!

however retro sonic cleary uses a dc dc converter on their boards   (they also use the Tl072 aswell)




also just to confirm all single lt1054 chip ideas haven't worked under load,
this one below displayed all the specified voltages until once connected the volts dropped by half on both rails


this is the size of the dual lt1054 (minus the drop down diodes ) (on my other board)
so i feel at far less than $24  doesnt take up too many parts?
im not sure if i can get a smaller package 15v regulator aswell ie T0-92  instead of a T0-220 (the big one fits on my board but the smaller package only handles 100ma and i dont have any on me?
any suggestions regarding this too?

[rankot]

78L15 is in TO-92 case, but it can handle only up to 100mA.

Regarding circuit with one LT1054, I believe that maximum current that you can expect for stable voltage is 35mA on both rails.