i am in search for a small kit that produces -+9volt (100ma) from +12v. nothing fancy needed. i need this to fix a goof i made on some boards i have.

anyone know of any kits out there?

 

How about an LM7809 for the + and an LM7909 for the negative?

 

That or 5 diodes in series, something like a 1n4001. They should drop approx 3V.

 

How about an LM7809 for the + and an LM7909 for the negative?

regulators? where do i get the - voltage from?

the Linear LT1054 can give me the negative side, but i would have to make a board for the components. was looking for a off-the-shelf item that i could just pop in the components, solder, done...., etc.

 

How much current do you need? The 555 makes a dandy voltage doubler/convertor, if that is what you're looking for. The 78xx and 79xx regulators could take it from there.

I made the same mistake ThingMaker did, the usual convention for a dual power supply is +/- instead of -+.

 

i wasnt really looking for which components, but rather a off-the-shelf ready made pcb.

i can use the LT1054 in bi-polar supply doubler mode. i can feed it the +5 from my lm7805. i may be able to get the 12 needed components onto a small copper-land perf board, wire it by hand, and then encapsulate it with some MG epoxy i have. it will do the job, but as i mentioned, was looking for a ready-made pcb, perhaps one that has the layout for this LT1054 dupply doubler, etc.

i goofed on my op-amp power supply, so now i need to come up with a small "daughter" card that can supply +/- 9v (>5v, <-5v)

 

Do you need 100 mA at -9 or is the negative voltage just for bias?

My recent experience with Maxim chips (non-inductor, capacitor switch) is that you can get the -9V at 5 mA (e.g., MAX850 series)or -5 V at 125 mA (MAX 1680 series). If you really need -9 at 100 mA, you can cascade two of the MAX1680s (see datasheet). John

 

How many of these pop-in adpaters do you need? Have you seen the SMD-IC adapters that have a bunch of solder pads for adding components. You can also add pins so you get a plug-in device. I can't find a brand on mine. I may have gotten them from Jameco. John

 

op-amp(ina114) supply is +/-2.2mA, and i have 6 of them.

i need 30 "fix that error" boards.

i know there are those perf boards that have strips of lands connected together and then you just cut across a track to make the circuit, etc, forget its name though.

 

i know there are those perf boards that have strips of lands connected together and then you just cut across a track to make the circuit, etc, forget its name though.

They are not perf boards. Jameco part#215491 is just one of many examples. They are 1/32, fiberglass, with a nice pattern for the IC and just lands that you could add the caps too with appropriate shorts (zero-ohm SMDs ?). In catalog 274, it's page 206. I have used a few of them. Of course, making 30 would not be fun. John

 

There was a +DC - -DC converter on the market some time ago I recall it was an ICL7660. The negative voltage got developed on a 10 uF tantalum cap. It mirrored the positive input, with a limit of 10 volts, so you would have to reduce the +12 (assuming you can find one). Jameco is the catalog of last resort.

 

Take a look here:
http://www.mouser.com/Search/ProductDetail.aspx?qs=35zkduByVmgdja99sYzc3A==
Murata, 12v in, +/-9v out @ +/-111mA, $14.
Then there's this:
http://www.mouser.com/Search/ProductDetail.aspx?qs=Z7IUn5gUMVNP8y%2bxli9kPg==
Murata, 12v in, +/-9v out @ +/-55mA, $8.76. That'll git 'er done.

 

you guys are awesome.

muRata just too expensive at ~$14.

the LT1054 was about $4 and needed 12 components total to net me 2v and -(2v)

the ICL7660 for about $1pdip ($0.63 for smt)with a couple of caps and diodes will net me ~2v and -(v) outputs, which will get me ~9v and -5v. perfect.

thanks guys, you are saving my prototypes from becoming fancy coasters. now i just need to find those strip pc boards. the bottom side has strips of lands all soldered together, then to cut the strips to create the circuit....

 

now i have to choose diodes and caps.

1. i have 1N4148's (200mA), are they ok?
2. caps? i have large supply of 22uF/25V electrolytic? are these ok? i see ripple is a factor of C2 ESR. my IA's are filtered well on the + supply pin, i'll have to add a filter cap to the - supply pin.


i'm building figure 20, page 10.
http://www.jameco.com/Jameco/Products/ProdDS/1139469.pdf