please help with over voltage protection?

[iainpunk]

so i have an overdrive design which requires a very specific IC and this IC will blow up if the supply voltage exceeds 16v.
that would not be a problem at all if only 9v power supply's were in use, but i see more and more people using 18v supplies.

i have a few 12v zeners, but regulating down with a resistor and still being able to deliver the needed current when on 9v, dictates that the resistor has to dissipate quite a lot of power to cope.

i'd rather not use a ''crowbar'' type protection circuit, and also, low parts count is appreciated, as i dont want to double the amount of components

is this just a risk builders take, or is it common to include some voltage protection?

cheers

[antonis]

How much current is needed for particular IC..??

[iainpunk]

How much current is needed for particular IC..??

the circuit pulls about 35mA form the 9.6v supply

cheers

[iainpunk]

i feel like a slight idiot for not thinking of this simple circuit:


i can probably get away with using a 2n2222a, a 1k and a 12v zener

cheers

[niektb]

So you don't mind the standard voltage drop when running it on 9V? (not sure what kind of chip it is and what it needs)

[iainpunk]

Ow, its a bipolar/CMOS hybrid chip, (not a 4000 series).
I had one die on me when i fed it 17.5 volt.
It works / sounds alright down to 7 volt, so a bit of loss in the power supply doesn't keep me awake at night, haha

Cheers

[niektb]

In that case you could also throw in a standard LDO haha for improved noise filtering and regulation etc haha

[composition4]

TLC2272?

Anyway here's my scheme I'm using on a pedal I hope to go commercial with... Next to no voltage drop, voltage limits itself at around 13v, no-harm reverse polarity protection... Might work for you, might be overkill



Jonathan

[antonis]

I think Iain said "low parts count"..

[composition4]

Come on, there's at least 20 words in his original post. Am I really supposed to read everything before making an ill-informed suggestion?

[iainpunk]

Come on, there's at least 20 words in his original post. Am I really supposed to read everything before making an ill-informed suggestion?

Yes you should, hahaha.

Im hesitant about adding 3 parts, let alone 8.
Still appreciate the effort tho. That regulation scheme has 8 components, thats more than half of the amount of components i have in this overdrive. Haha

Cheers

[toneman]

check out the LM317 adjustable regulator.

comes in TO220 case for heatsinking.
also comes in TO92 (transistor)type small case.
add 2 resistors to set the limits. done. 3parts.
probable a couple of caps at in and out would be good too.
cheers
RAMS or BENGALS?

[duck_arse]

It works / sounds alright down to 7 volt, so a bit of loss in the power supply doesn't keep me awake at night, haha

Cheers

all the larffink in this thread is keeping me awake at night.

[iainpunk]

Does the LM317 let through current if its supplied with less than it regulates to? Like if i were to set it to 14v and i fed the circuit only 9 volt, does the lm317 still supply whats left to the circuit?

larffink

what's that?

RAMS or BENGALS?

Am i missing something?

Cheers

[duck_arse]

Does the LM317 let through current if its supplied with less than it regulates to? Like if i were to set it to 14v and i fed the circuit only 9 volt, does the lm317 still supply whats left to the circuit?

larffink

what's that?

RAMS or BENGALS?

Am i missing something?

Cheers

larffink = laughing

RAMS or BENGALS = an american sporting endeavour