This example describes the AC voltage stabilizer , automatic voltage regulator function , its input voltage range of AC 120-260V, output voltage of AC 220 ( 1 ± 10%) V, Output power 300-1000W ( as from waxy Power transformer and relay contact current capacity may be) . Circuit works The AC voltage regulator circuit from the power circuit and the voltage detection control circuit , as shown in Figure 5-42 . Power supply circuit consists of step-down capacitor Cl, C2, resistor Rl, rectifier diode VDl-VD4, filter capacitor C3,V voltage regulator diodes and transistors formed VS . Voltage detection circuit consists of four operational amplifier integrated circuit IC (Nl-N4), resistors, full -R7, capacitors C4, point potentiometer P, relay Kl-K4, since the transformer T and the diode elliptical VD5-VDlO composition . Nl-N4 are connected to form voltage comparator ; R2-R6 series voltage divider circuit composed of , for Nl-N4 inverting input to provide the reference voltage ; R7, RP, VD5, VD6 and composition of C4 input voltage sampling circuit , for Nl-N4 Provide sample voltage ; Kl-K4, VD7-VDlO and T control the implementation of the circuit component . When the input voltage is close to normal 220V when , Nl-N4 big end positive phase input voltage are +22 V, Nl output low , N2-N4 are the output high , KI-K4 are in a free state , the input Voltage by the Kl-K4 in the normally closed contact output directly to the load ( electrical equipment) , without the need to boost or buck by T treatment . If the input voltage is low , so that Nl-N4 positive phase input voltage is lower than the N4 inverting input (lC 13 feet ) of 14.5 V reference voltage , then the output of Nl-N4 are low , Kl smoking Together , the normally open contact connected to (K2-K4 is still in the release of state) , the input voltage through the normally open contacts Kl buy additional winding on the T, W4 , by Wl-W3 winding voltage to output , rose at this time Pressure is relatively high, corresponding to the minimum AC input voltage . If the input voltage is low , so that Nl-N4 positive phase input voltage falls below the inverting input of N3 (IC g- feet ) of 17.5 V reference voltage is higher than 14.5 V , then the N4 high power output Ping , Nl-N3 are the output low , K2 pull its normally open contact connected to (Kl and K3, K4 in the release of state) , the input voltage through the normally closed contacts Kl and the burning of the normally open contact plus In T, W3, W4 winding , through Wl, W2 winding voltage to output a high step-up at this time . If the input voltage is low , so that Nl-N4 big end of positive phase input voltage is less than N2 inverting input (IC 6- feet ) of 21.5 V reference voltage is higher than 17.5 V , then the N3 and N4 are Output high , Nl and N2 output low , K3 pull its normally open contact connected to (Kl, K2 and K4 in the release of state) , the input voltage by the Kl, K2 and K3 of the normally closed contact of Normally open contact added to the T, W2-W4 winding , winding through Wl boost the output , then the step-up than the minimum . If the input voltage is high, and so Nl-N4 positive phase input voltage is higher than the inverting input Nl big end of the 23.5 V reference voltage , then the Nl-N4 are high output , K4 pull its normally open contact Head turn (Kl-K3 are in the release of state) , enterVoltage by the Kl-K3 of the normally closed contacts added to the T, Wl , on a winding W4 , Wl winding down through the output . Components Selection Rl and R7 are selected 1/2W metal film resistors ; R2-R6 are all made of precision metal film resistors . RP use of organic solid variable resistor . Cl and C2 are selected voltage value is greater than or equal to 400V in the CBB capacitor ; C3 5OV selected voltage value of capacitors ; C4 selection of capacitors for voltage value of 25V . VDl-VDlO 1N4007 type silicon rectifier diodes are used . VS selected IW, 24V silicon voltage regulator diodes . V use S805O or C8050, 3DG8050 silicon NPN transistor . IC type LM324 quad op amp used integrated circuits . Kl-K4 are all made of the coil resistance is greater than 2k0 ‘s 24V 100 current relay , the contact current capacity should be based on the size of the output power . T with E -shaped core and high- strength magnet wire wound : Wl-W3 windings are used fO · 51-f1 · Omm of enameled wire wound 150 turns each ; W4 windings f1 · 1-f1 · 5lmm of enameled wire wound 650 turns . Circuit Debugging Circuit installed, the AC input power supply voltage regulator on the one hand terminated load power regulator. AC input voltage is first raised to 220V, adjust the resistance RP , so Nl N4 positive phase of a input voltage +22 V. Then reduce or increase the input voltage to see whether the corresponding relay are working properly. If it is not working properly , you should check the sample circuit components each resistor voltage divider circuit parameters are normal.