The general dual power supply (positive and negative symmetrical power supply) does not have a continuously adjustable function, which is inconvenient for use. In this paper, a 7815 and a 7915 three-terminal regulator are connected symmetrically to obtain a set of positive and negative symmetrical regulated power supplies, and the output voltage values ​​can be individually adjusted or adjusted simultaneously. Heating Element Temperature Control,Electric Grill Temperature Controller,Thermostat For Heating Element,Oven Capillary Thermostat Foshan City Jiulong Machine Co., Ltd , https://www.jlthermostat.com
As shown in the figure, the AC double 18V voltage output by the transformer is rectified by D1~D4, and C1 and C2 are filtered to obtain the DC voltage. The center tap of the dual power supply of the transformer is used as the common ground terminal, and then the DC voltage is positive and negative respectively. The pole is connected to the 1 pin of the 7815 and the 3 pin of the 7915. Pin 3 of 7815 is connected to sliding contact "d" of potentiometer W2, and pin 1 of 7915 is connected to sliding contact "C" of potentiometer W1. When the contact "C" is slid to the "0" terminal ground, adjust W2 to get the positive variable voltage of "+6~+15V" from the "a" end; if the contact "d" is slid to "0" "End grounding, adjust W1, get "-6 ~ -15V" negative variable voltage at "b" end, replace W1, W2 with coaxial potentiometer, will get positive and negative symmetrical adjustable power supply, The output voltage value is continuously adjustable from ±6V to ±15V, which can achieve the purpose of synchronous adjustment.
The heat sink should be installed on the 7815 and 7915 three-terminal voltage regulator block of this circuit. The power of the transformer depends on the power of the electrical appliance.