Question about producing 24 volts form 12 volt PS

[mamech]

Hello Everyone

How I can produce 24 volts from a computer power supply that has 12 and -12 volts ?

Sorry my question may look like trivial.

 

[blueroomelectronics]

How much current do you need?

 

[mamech]

I am not sure. I need the 24 volts to operate an SR2 B201BD smart relay. It is written on it :
Power:
24VDC 6W

Output rely:
24VDC 8A
240VDC 8A

 

[Reloadron]

With a power requirement of 24 V and 6 Watts it doesn't require much current. However, I would go with a 24 VDC supply referenced to ground as I would worry about the DIO. The DI is designed for 24 VDC inputs and they should (I believe) share the power common. I would find a DIN Rail mounted 24 VDC single ended supply for it. Not saying the split won't work, only that I would not do it personally.

Ron

 

[Jaguarjoe]

Plan "A":

Buy 2 of these:

**broken link removed**

Wire their inputs in parallel and connect to your +12 volt high amp source.
Wire their outputs in series to give you 30 volts at 1 amp.
Your solenoid consumes 6 watts, this is 0.25 amps at 24 volts.
Sticking a dropping resistor in series with the solenoid to eat that extra 6 volts you have:
R = E/I = (30-24)/0.25 = 6/0.25 = 24 ohms.
It dissipates P = EI power = 6*0.25 = 1.5 watts. To keep it cool derate that wattage by a factor of 2.5 or 3. You'll need a 24 ohm, 5 watt resistor. This is from the same place that sells the converters and will work great for this:

**broken link removed**

Be sure to stick a commutating (or freewheeling, or back emf) diode like a 1N400x across the coil to eat the coil's spike when it shuts off.

Plan"B":

If the - 12 volt power supply you have can supply that 0.25 amps (+ 12 supply is usually good for beaucoup amps) AND the + and - share the same common, then just wire your solenoid to the + output and to the - output.
Don't forget the diode.

 

[Reloadron]

Solenoid? What solenoid?

I thought he had one of these units. Did I miss something.... Again?

Ron

 

[mamech]

Plan "A":

Plan"B":

Don't forget the diode.

sorry, which diode do you mean ? and where am I supposed to put it ?

 

[mamech]

@Reloadron:

There are no solenoids. It is a (small) plc device, called smart relay as you said.

 

[Reloadron]

@Reloadron:

There are no solenoids. It is a (small) plc device, called smart relay as you said.

I am aware of that. It should be the device I linked to in my later post. I was wondering where Jaguarjoe came up with a solenoid.

Anyway, because of the reasons I mentioned I would use a single ended 24 VDC supply as I mentioned and not use the split supply. Pretty much as I mentioned, based on what you have.

There is no diode or need for a diode. The diode would have been used if there was a solenoid. Don't worry about it. Just some minor, humorous confusion.

Ron

 

[Jaguarjoe]

I was wondering where Jaguarjoe came up with a solenoid.

Just some minor, humorous confusion.

Ron

Well, its like my old friend Roseanne Rosannadanna used to say, "Nevermind!"

Kinda like when you wake up after a hard night at the bar and you look over and say, "Where did that come from?"

 

[Reloadron]

Well, its like my old friend Roseanne Rosannadanna used to say, "Nevermind!"

Kinda like when you wake up after a hard night at the bar and you look over and say, "Where did that come from?"

Been there and done that.

Ron