help needed for generation of +-12V power supply from 12V battery

[amit_kr]

i want to generate -12V to 0 to +12V power supply from a 12V battery. if anyone have any idea how to do it plz help me

 

[Nigel Goodwin]

i want to generate -12V to 0 to +12V power supply from a 12V battery. if anyone have any idea how to do it plz help me

You might have more luck if you give the specs required, what you've put so far is completely useless!.

If you don't know the specs?, then tell us what it's for!.

 

[amit_kr]

i want +-12V for generation of squarewave from IC555

 

[Nigel Goodwin]

i want +-12V for generation of squarewave from IC555

You're still not telling us anything useful!.

 

[dknguyen]

Use two 12V batteries connected in series to form 24V, but treat the common connection between the two as the ground. Attaching something between the ground and the opposite terminal of either terminal will give you +12V or -12V. Attaching something directly across both batteries will give you the regular 24V. Then regulate the voltage coming out. Can't say much more with more details...

It's kind of risky and unreliable to regulate a 12V battery to put out 12V isn't it? Since the raw voltage is so close to the regulated? The battery could drop below the regulated 12V output and cause certain regulation mechanisms to not work properly.

 

[phamthaihoa]

i want to generate -12V to 0 to +12V power supply from a 12V battery. if anyone have any idea how to do it plz help me

- You can use DC to DC converter IC such as MC34063.

You can generate -12,+12V from 5V or lower.

- Or you can connect in series three ICL7660 (charge-pump). You can see it on ICL7660 datasheet.

- You can use 555 to generate -12V, it need two diodes and 2 elec-cap and one zener diode.

 

[andrew_in_the_search]

12v squarewave?

i want +-12V for generation of squarewave from IC555

if you want a 12 squarewave(good slewrate, lo output current):

IC555
astable conf----------->pin(+)
LM 318----->(voilà), 12v squarewave.
6,5V(stab from +12)---->pin(-)

the LM318 can be compensated, nulled, etc. it´s a very good opamp to 15MHz. Download data from national semiconductor.

agn, if it´s what you want, don´t supply the -12v from switchers.
for a good pulse shape go linear.

hope this help you.
after all, a squarewave is from zero same up, same down 50%DC (what you'll get from above).

keyboard will not gonna bite you, boy...

cheers/andrew

 

[hjames]

I'd suggest against using a 7660 chip - they're typically rated for 10V, although there are some varieties which have an extended voltage range (Intersil ISL7660A, https://www.intersil.com, you'll need to check the datasheets for details.

 

[audioguru]

The max supply voltage for a 555 is only 18V. Using a positive 12V plus a negative 12V totals 24V which is way too high.

Even if you used a supply voltage of 18V then at its max output current of 200mA its output voltage is only 13V peak to peak.

 

[hjames]

If he's using a 555 in a voltage inverter config the 555 only sees 12V, so it's okay. But I agree that the output voltage is likely to be somewhere around -10V, unless the current draw is really low, and he's using schottky diodes.

 

[Nigel Goodwin]

What's the point arguing about it?, he's never even bothered giving us his requirements yet!.

 

[hjames]

Well, nit's exist to be picked. Obviously we can't answer the guy's question (or questions since things it isn't clear what he wants), but spending 30 sec clarifying things never hurt.

After seeing all the questions about voltage inverters, I'm kinda tempted to document it in hopes of being able to point to the "FM" in future posts.

 

[oldtimer]

Use the 555 as an astable feed the output into a mosfet /transformer to step up to about 35 Volts rectify and fiter it and use a 7812 and a 7912 to give you the -and + 12V.

 

[Oznog]

Nigel's right. How much current do you want to draw, and what is the load? Will the job allow you to center tap 24v to do this? What are you asking for?