Ceiling fan electronic timer circuit

(1) Introduction to circuit principle The ceiling fan electronic timer circuit consists of a power supply circuit, a delay control circuit and a monostable trigger control circuit.
In the circuit, the power circuit is composed of the electro-oscillatory switch Sl, the step-down capacitor C, the bleeder resistor Ri, the Zener diode vs, the rectifier diode VD and the filter
capacitor C2; the delay control circuit is composed of the transistor VT, the resistor R2, where and It is composed of capacitor c3; the monostable trigger control circuit is
composed of timing selection switch S2, capacitor G, G, time base integrated circuit IC, resistor R; ~ R8 and thyristor VTH. After the AC 220V voltage undergoes (1l step-down
current limiting, VD rectification, C2 filtering and vs voltage stabilization, it provides 12V DC working voltage for xrr and lC. When the power is first connected, the -12V
voltage charges to C through R2, but Because the voltage at both ends of C3 cannot change suddenly, VT is in a cut-off state, and the ③ pin of I(: outputs low level. VTH
is not conductive, and the ceiling fan motor M does not rotate. After about 3-4s, the voltage at both ends of C3 rises to At 0.7V, VT is turned on, causing the ② pin of the IC to become
low potential, the monostable trigger circuit changes from a steady state to a transient state, and the ③ pin of 1C jumps to a high level, causing VTH to be triggered and turned on. , M is powered
on and running.
    S2 is used to select the timing time, with four adjustable levels of 15 rmn, 30min, 45min and 60min.
When S2 is placed in the "2" (30min gear) position, the 12V voltage charges c1 through Rs and S2 , causing the voltage of pin ⑥ of lc to rise continuously. When the 30min timing time is over, when
the voltage rises to 8V, the monostable trigger circuit flips over and returns to a steady state from the transient state. Pin ③ of lc becomes low voltage Level, so that VTH is cut off and M
stops.
    (2) Component parameter selection: 1/4W carbon film resistor or metal film resistor is selected for S. Polyester capacitor or CIIB capacitor with a withstand voltage of more than 400V is selected for
Ci; G is selected Aluminum electrolytic capacitors with a withstand voltage of 25V; aluminum electrolytic capacitors with a withstand voltage of 16V are used for c3 and C;
polyester capacitors or monolithic capacitors are used for G. 1N4004 or 1N4007 silicon rectifier diodes are used for VD. 1N4 742 or 2CW60 is used for vs. (1W,
12V) type silicon voltage stabilized diode tube.
VT uses 59013 or 3DG6
silicon NPN transistor. VTH uses
lA, 400V bidirectional thyristor.
IC uses NE55a or 561555 type
time base integrated circuit. Sl uses
ordinary AC power switch. ; S2 selects
a four-position key switch, and tEL can be shared
by Sl and S2 using a bipolar five-position band
switch.
    (3) The ceiling fan electronic timer
circuit is shown in Figure 3-28.