Adjustable Dual Output Positive & Negative Voltage Power-Supply Kit (Adj. output +/- 1.25V to +/-24 VDC) is an OEM electronics board that allows you to connect up to Dual 30V AC on one side of the board and get adjustable voltage regulated (VDC) on the other side.


Every facility should have a few of these boards handy. The boards will allow you to easily power all your HVAC controller, interface board and low-voltage equipments components (i.e. +/-0-10V, +/-12VDC, +/-15VDC, +/-24VDC). The Terminal Block TB connector is included and makes it easy to use. 





Standard Board




With optional high-current configuration






Some of the features of the PS (LM317 and LM337) include: 1% output voltage tolerance, max. 0.01%/V line regulation, max 1A output current, adjustable output down to +/-1.25V, current limit constant with temperature, 80 dB ripple rejection, output is short-circuit protected.


The board includes protection diode prevent capacitors from discharging thru the regulator during an input short circuit.


Heat sinking block is usually require when pulling current > 250mA (optional). Heat sink are manly manufacture from Aluminum material.


Final Note: As a general rule the input voltage should be limited to 2 to 3 volts above the output maximum voltage. The board can handle up to +/-36 volts input, be advised that the power difference between the input and output appears as heat. If the input voltage is unnecessarily high, the regulator will overheat. Unless sufficient heat dissipation is provided through heat sinking, the regulator will shut down. Therefore, you will need to  mount a heat-sink on the regulator that is capable of dissipating the access heat produced. please also note, that the metal body of the regulators LM317, LM337 and LM338  (TO-220 package) is connected internally to the output leg of the IC (Not to Ground!).




Transformer with central tap (CT) configuration, see schematic below.



For our line of transformers click Here or for Isolation AC Power Transformer board click Here


Please drop us a line at and let us know where you use this unique dual power supply board. Or, of course, if you have any adjustments deemed important--and one of our engineers will be happy to help you achieve them.


Description and SKU#


Dual +/- 1.25-24VDC PS, Input up to 30VAC & adj. output  +/-1.25V to +/- 24V/1A, w/LM317/337 TO-220


EID-K-VRD-125X-24V-1A-ASM Fully assembled




Dual +/- 1.25-24VDC PS, Input up to 30VAC & adj. output  +/-1.25V to +/- 24V/2A/1A, w/LM338/337 TO-220


EID-K-VRD-125X-24V-2A-ASM Fully assembled with high current diode option