Reduce 24v DC to 18v DC

Hi,

I am new to electronics and I would appreciate your assistance, I have a Lambda LNS-Z-24-J power supply and I need to reduce the voltage to +/- 18-20v I called tech support at Lamdba and they suggested a voltage divider or regulator, as I have no knowledge can anyone provide me with instructions on how to build this item.

Thank you.
 
Good point...

I am building an FM Stereo Exciter which includes the Transmitter (13.3 -16Vdc 300mA max) a Limiter (15Vdc 300mA) and a Stereo Encoder (13-15Vdc 300mA)

These 3 boards are combined on one PCB and the manufacturer recommends a 18-20VDC 700mA regulated Power Supply.

Hope this helps.


Thank you

Chris
 
hi finestocean,

These are very simple very common circuits that will achieve 18V +/- like you need.
The upper is using voltage regulators, ignore the part codes as they arent 18V refulators.
You will have to find +18v and -18V regulator I.C' part numbers yourself as i dont know any off my head. You may have to even get a variable output regulator. If you use regulators make sure you buy ones that will handle 1 amp or more.

But it is easier to use circuit 2 really, the diodes i used are 18V zeners and are very cheap, you can substitute the mfor and other 18V zener.
Make sure they can handle at least 1 amp of current through them to be safe.
This circuit will provide +and - 18V DC at up to just under 800mA per rail before the zeners start losing their regualtion, test it with a 24 ohm load to check it works for you.

Regards
Craig
 

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But it is easier to use circuit 2 really, the diodes i used are 18V zeners and are very cheap, you can substitute the mfor and other 18V zener.
Make sure they can handle at least 1 amp of current through them to be safe.
This circuit will provide +and - 18V DC at up to just under 800mA per rail before the zeners start losing their regualtion, test it with a 24 ohm load to check it works for you.
A zener shunt regulator is really only useful for very low current supplies. Check out what happens if the load is disconnected: .79 A of current flows through the zener, causing over 14 W of power dissipation. Most zeners are rated at 1 W, many at just 1/2 W. Those zeners will release their magic smoke in a matter of seconds. And everyone knows that once you let the magic smoke out, you can't put it back in.
 
finestocean said:
I am building an FM Stereo Exciter which includes the Transmitter (13.3 -16Vdc 300mA max) a Limiter (15Vdc 300mA) and a Stereo Encoder (13-15Vdc 300mA)

These 3 boards are combined on one PCB and the manufacturer recommends a 18-20VDC 700mA regulated Power Supply.

I'm slightly confused here as your original request was for a dual-rail -18V_0V_+18V supply which has been answered.

From the look of the amendment quoted, a single-rail regulated 15V supply is more in line with what you need, unless the pcbs have components to reduce the 18-20V recommended to the quoted levels. :confused: