48 volts to 44 volts

[mick_e]

If a had a 48volt power pack, how would I limit the output to 44v?
Sorry for the simple question.

[Sammas]

Hey Mick.


...erm. Why?

There are a bunch of ways to probably do it... and a bunch of ways probably not to do it, but it
all depends on the application. Is the power pack outputting ac or dc?

[mick_e]

Well I just got hold of a couple of yamaha pm1000 modules and they are meant to run on 44v. Some of the components have a maximum voltage rating of 50, so im thinking 48 may be pushing my luck just a bit. Ive got an adapter that outputs 48vdc at .75A. Could I run a couple of modules of this? Whats the standard way of running to units from one source, in series or parallel?

[no-fi]

is the adapter regulated or unregulated?? if it's regulated, 48V should be fine.

run multiple units in parallel. - running 2 in series with your 48V will only give you 24V per unit, and will give you huge problems with ground references if there's not strict transformer inputs and outputs for everything....

[mick_e]

Thanks a bunch.

[chris p]

Mick E

There's two basic ways to do this, if you really want to. The first requires that you know the resistance of the channel strip power supply (connect a multimeter between V+ and 0V of the card). You then put a dropping resistor in series with of the V+ terminal to drop the voltage. To calculate the value of the resistor, you need to think V=IR. Say your card shows up as 20K resistance, and its designed to run on 44V. So 44(V) = I * 20,000 (R), or I = .22A current draw (220mA). You then want to calculate how to drop the voltage by 4V and again V=IR, so 4 (V) = .22 (I) X R, or R= 18.2 ohms. The power loss (W) through this resistor is W= I^2 * R = .22 * .22 * 18 = .87W, so in this example you'd need at least a 1W resistor (not the run of the mill 1/4 or 1/2W). You need to substitute in your actual figures, of course, to work out your R and W

The second is to create a regulated circuit using something like a LM317 adjustable voltage regulator. You could easily build such a beast using a JLM PowerStation PCB and a few components. This is the better engineered solution.

[Gian]

What about a zener diode?

Here is a 43V one from rs
http://australia.rs-online.com/web/sear ... &R=4854069

[rob]

JLMs simple zener regulator is perfect for this job. Stuff as per instructions and use the trimpot. Adjust the trimpot for 44V output.

[mylesgm]

joe's kits make most of my DIY (especially power stuff) a piece of pie. And I love pie. I've built maybe 15 p/s of differing types, a couple of DI's, go betweens and the 99v pre, dingo etc. if it suits your application then I just go with his kits and don't think about it anymore.

M

[mfdu]

just reduce the diameter of the throttle inlet, and you'll be rockin.











oops. wrong forum.

[mick_e]

Cheers guys. I think im gonna go with the jlm kit.