Hi all,
Question to the technical geeks if I may:
I want to power a headphone amp (a Behringer p2 that takes 3 volts from 2 x AAA batteries) from a 9v tap on my Cioks pedalboard power supply. I remember from school that this is a job for a potential divider: if I put two resistors in series across a 9v output of the power bock, such that the ratio of resistor 1 to resistor 2 is 2/3, I will get the required 3v potential across the smaller resistor.
My question is: what are appropriate absolute values for the two resistors? Obviously, if they are both small, the quiescent current drain on the 9v source will be too high; but equally, if they are big, there may not be enough current to satisfy the headphone amp.
Any suggestions as to appropriate values for the two resistors? (I don't know what the current consumption of the headphone amp is, but I'm guessing from the fact that it's powered by AAA batteries that it's low: 10mA maybe??)
Comments
https://www.ebay.co.uk/itm/162289623433
HTH,
R.
Eqd Speaker Cranker clone
Monte Allums TR-2 Plus mod kit
Trading feedback: http://www.thefretboard.co.uk/discussion/60602/
You could just stick a 5v6 1W zener in series. Better would be a 7805 regulator. I very much doubt the amp would be bothered by 5V and that would give you more headroom. Or, check the data sheets on the LM317 adjustable regs? I just feel a cheap dc-dc switching converter might be noisy for headphone use?
Dave.
And for £1.99, a ready-built module is worth a try!
Eqd Speaker Cranker clone
Monte Allums TR-2 Plus mod kit
Trading feedback: http://www.thefretboard.co.uk/discussion/60602/
That module is 48 * 22 * 12 mm - might just be a bit big. Also, heat/ventilation.
Eqd Speaker Cranker clone
Monte Allums TR-2 Plus mod kit
Trading feedback: http://www.thefretboard.co.uk/discussion/60602/
So just a regulator and 2 resistors with maybe a cap on the output, that should fit in there
Sorry, don't understand the objection?
Dave.
No real objection, just that the OP wasn't confident enough to figure out what resistors to use so probably wouldn't be able to figure out how to use a zener or design a 7805 circuit. That's all.
R.
Eqd Speaker Cranker clone
Monte Allums TR-2 Plus mod kit
Trading feedback: http://www.thefretboard.co.uk/discussion/60602/
Ah! Well I have a process in such matters for forums! K.I.S.Sir. Tell OPs the options and then let them come back and ask further questions like.."Ok, so HTF do I do that?"
I have wasted my time before, going into intricate detail only never to see the guy or gal again!
Dave.
Ha ha - I appreciate all the suggestions and am learning a bit about “modern” electronics by looking up these various devices. When I was a kid I played with simple electronic circuits (and I’m wizard at soldering!) but devices like mini voltage regulators and even zener diodes are all pretty new to me.
I discovered many years ago that you need to pick your battles.
If you want to learn about electronics then look into how to calculate resistor values, and why that's not a great way to drop-down voltage, and investigate zeners and voltage regulators, etc. It's fun.
If you want to just get a job done, buy something to do it and move on.
Focus on what is most important to you.
R.
Eqd Speaker Cranker clone
Monte Allums TR-2 Plus mod kit
Trading feedback: http://www.thefretboard.co.uk/discussion/60602/