Chemical mixer circuit

The chemical mixer circuit has functions such as speed-adjusted stirring, temperature-adjusting and timing alarm, and can be used in chemical, steel and other industries.
  (1) Circuit working principle The heating magnetic stirrer circuit consists of a power supply circuit, a stirring motor control circuit, a heating temperature regulation circuit, a stirring
motor speed regulation circuit, a timing alarm circuit and a timing control circuit, as shown in Figure 7-11.
    The power circuit consists of power switch Sl, power transformer T, bridge rectifier UC1, and resistor R. , power indicator light HL1 and filter capacitor island
.
    The heating and temperature regulation circuit consists of the heating control switch S3 (S3-1. S3-2), electrical contact thermometer Q2, resistor, capacitor C and Ca,
transistor VT2-VT5, electric heater EH, and constant temperature indicator light HL3, heating indicator light HIA, diode VD2, relay K3, potentiometers
RI and RP3, thyristor VTH and bridge rectifiers UC2 and UC3.
    The timing alarm circuit is composed of transistor VT1, resistor R3, capacitor 0, relay K2, diode VD1, buzzer HA and Kl's control
contact Kl-2.
    The stirring motor speed regulating circuit is composed of stirring control switch S2, potentiometer RP1, resistor R2, diode VD3, stirring indicator light HL2 and motor
M. :
    The timing control circuit is composed of timer Ql and relay Kl.
    Turn on the power switch S], and after the AC 220V voltage is stepped down by T, three sets of AC voltages are generated on the W2 ~ W5 windings. After the AC voltage on the W3 winding is rectified by -UC1 and filtered by G, it provides +12V working power
for the timing control circuit, delay alarm circuit and temperature control circuit
.     After the timer Ql is turned on, the relay Kl is energized and closed, the normally closed contacts of Kl-l and Kl-2 are disconnected, the normally open contacts are connected, and cI is charged.
    After S2 is turned on, the AC voltage generated on the W2 winding of T is rectified by VD3 and current-limited and reduced by RP1, and then supplied to the stirring motor M, and M drives
the stirring blade into the stirring working state.
    After S3 is connected, VT3 is turned on, K3 is energized and closed, and
its normally open contact is connected. The AC voltage generated by the W4 and w5 windings of T is current-limited by Cl and RP2 and rectified by UC2, and then passes through the normally open contact of K3. and S3-1. RP3 provides the trigger voltage for VTH to turn on VTH, and
the AC 220V voltage provides the working voltage for the electric heater EH through UC3 and VTH.
    Adjusting the resistance of RP1 can change the working voltage of M, thereby changing the speed of stirring, achieving the purpose of stepless speed regulation. Adjusting
the resistance values ​​of RP2 and RP3 can change the conduction angle of VTH, thereby changing the level of the EH operating voltage to achieve the purpose of stepless temperature regulation.
    When the heating temperature is lower than the control temperature value set by the electric contact thermometer Q2, the electric heating contact of Q2 is in a disconnected state and V2 is cut off. When
the heating temperature reaches the control temperature set by Q2, the electric heating contact of Q2 is turned on, VT2 is turned on, VT3 is cut off, K3 is released, VTH is cut off
, and EH is powered off to stop heating. At the same time, VT4 is turned on. VT5 is cut off, HL3 is on, and HL4 is off, thereby achieving the purpose of automatic temperature control.