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Step up computer power supply to 24V

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2600:
I'd be careful of using the PSU power supply and the daisy chaining will only work if the supplies are isolated.  May work, you just have to be careful.


1A is what I figured.  There are things out there probably, but off hand I'm not familar witht something that will get you that much current.  You could try the charge pump or a DC-DC converter.  DC-DC converters easily have the conversion.  Then use a really BIG capacitor so that you get enough current.  Not sure if you can wait for the capacitor to charge back up.
(Derrick Renaud mentioned using a Big capacitor a couple of months ago, I forget what he paired it with so you may want to give that thread a search)

hanelyp:

--- Quote from: rdagger on June 22, 2006, 11:35:43 am ---I not sure on the amps but probably about 1A to control a 24V solenoid.
--- End quote ---
How many solenoids and what resistance for the coils?  Time to get out the trust multimeter.  Divide 24V by the coil resistance, then multiply by the number of solenoids to get the amps you'll need.

Another possability, your 24V solenoid might work properly on 12V.  You can't hurt it by trying.

rdagger:
The resistance on the solenoids are 240 ohms.  Therefore, according to hanelyp they should require .1 amp each.  Although, I spoke to an engineer and he told me that solenoids have an "active" resistance called reactance and you can't put an ohmmeter on them and simply measure resistance. Their resistance varies with the frequency of the applied signal - hence "active" resistance.
After some research, I built a voltage double circuit (see the pic).  I could probably use a better PNP but I used parts that I had on hand.  The circuit works.  My 12 volt p/s (actually 11.75V) can not drive the solenoids at 12V.  However, after hooking up the doubler circuit the solenoids works, abet slightly sluggish.   The circuit is putting out 22.75V.   I measured the current in series and each solenoids is only pulling .05 amps.  I suppose that this is misleading.  I think the solenoid probably pulls .1 A or higher when firing, but then requires less current to stay open.  Unfortunately, my meter is too slow to measure the actual current pulled during firing.
Any suggestions on how to make the circuit more efficient?

rdagger:
I finally got the circuit working with 2 solenoids.  It turns out that C1 and C2 were the problems.  Lowering them from 100nF to 10nF instantly doubled the voltage I had available for the second solenoid.  Also increasing C3 provided an additional modest boost in performance.  I tried even larger values for C3 and C4, but there was no additional benefit.  Here is a schematic for the improved circuit.  I could have upgraded all the transistors to get an additional .5 volts, but it did not seem worth the cost.

rdagger:
Here's a 3D rendering of how the board will look.

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