The timer is characterized by: (1) regular cycles wide. Boot time and hold time from seconds to 2h, respectively, continuously adjustable. (2) boot up time, respectively, in two colors, each of 10 sub-light-emitting diode display work, the remaining time at a glance. (3) the timer can be a single work, but also duplication of effort. (4) When the timer can not use ordinary power outlet. (5) Timer selection of easy to purchase common gate circuits, flip-flop, counters, etc., is very suitable for large secondary schools with teaching practice.
  How it works: the P2, P3, C1, W1 etc. A oscillator, F5, F6, C2, W2 etc. B oscillator, IC2 for the first counter, IC3 is the second counter, IC3, respectively, 10 and the output negative then the two groups together all 10 LEDs, respectively, through their negative current limiting resistor R9, R10 connected to the VT2, VT3 bistable flip-flop composed of two output endpoints.
  Work process: IC2, IC3 end of the Qing 0 respectively, then there is R5, C3, R6, C5 circuit composed of the two counters to 0 set to 0, bistability in the VT3 base connected with capacitor C10. Therefore, the base of power was instantly VT3 low potential, the VT3 end, the collector was conducting high potential to VT2, VT4 because VD8 deadline to turn and relay, the machine is energized. At the same time, clamp diodes VD3 to work close to A oscillator; VD5 turn the oscillator B, F6, is clamped in the low input, so the oscillator B to stop vibration, the oscillator pulse signals A, F1 back to the door by the VD2 phase, after K1 to the IC3 of EN negative pulse input terminal, each time the counter is a number of oscillation, the output side order by Y0 ~ Y9 positive pulse output, respectively, as collector for the VT2 low potential, so the composition of the X1 ~ X10 LED array is followed by light, when the pulse count to the tenth (X10 lit), IC3 12 feet into the binary bit-side gives a positive pulse, it is by the door F4 After reverse-phase into a negative pulse to trigger by the C8 and C9 VT2, VT3 bistable circuit composed of flip so that the cut-off into VT2, VT3 conduction, VD8 turn to VT4 close, the relay off, the whole unit is in standby mode, at the same time because of VD3 conduction, the oscillator A is clamped to stop the input vibration. As the VT2, and its high potential to VD5 end collector, enter the lift gate clamp F6, oscillator B to work, the output by the VD1, F1 to the IC3 to count, but this time turn VT3, VT2 deadline, so Although the IC3 of the Y0 ~ Y9 still positive pulse is given the order, but now X1 ~ X10 is not bright, but X11 ~ X20 R10 received by the collector VT3 (low potential), so the X11 ~ X20 lights turn to the X20 light later, the same 12-foot IC3 carry pulse is given by the F4 phase reversal, once again the bistable flip so close VT3, VT4 conduction and relay, the circuit is energized again.
  From the above we can see that the work cycle of the timer, that is, bistable flip cycle, 10 pulses per output oscillator, bistable flip only once, so the oscillator need not have a large RC time constants . Practice has proved that, when R take 6MO, C take 5µF cycle time can trigger flip over ten minutes, in order to further expand the time range, the aircraft was added in front of a counter IC3 IC2. When the K1 when placed X10, F4 negative pulse is sent to the IC2 of the EN-side, and IC2 12-foot side carry positive pulse is given by the carry inverted phase after VT1, the K1 is connected in the IC3 of the EN side , so that 10 pulses sent F4, IC3 only counted once, after the trigger pulse sent only 100 flip once, so that time period extended 10 times.
  By the F2, F3 oscillator consisting of only A turn in the VT2, VT3 cutoff relay, the circuit is switched work. At this point X1 ~ X10 lights were lit, the circuit can indicate the boot time and adjust the potentiometer W1 power can change the length of time, from F5, F6 B oscillator composed of conducting only VT3, VT2 power cut-off relay , the circuit is in standby work, then X11 ~ X20 lights were lit, you can instruct the circuit of standby time, while adjusting potentiometers W2 can change the length of standby time.
  The above is repeated circuit in the state, the machine can work in a single state, when to throw the K2 single state power, the circuit and repeat the same work, began closing VT3, VT2 conduction, VT4 conduction following Electric pull circuit is energized, the oscillator A to work, X1 ~ X10 lights were lit, but after the X10 display, IC3 gives the carry pulse, bistable flip-flop flip into conduction when the VT3 , VD3, VD4 were clamped, and VD4 K2 received through the input of oscillator B, F6, so that the two oscillators have been clamped, and to stop vibration counter to stop counting, because this time deadline VT4, relay off electricity, the circuit is in standby mode, thus completing a regular shutdown process.
  Machine circuit IC3, respectively, the output string has VD12 ~ VD20 9 diodes, to prevent interference between the various outputs, two counter-side, respectively, carry through the C4, C6 connected to the circuit "0" side, to ensure send binary pulses, the counter can be reliably back to zero, that is, when one stops the oscillator, and the other to work, the counter from 0 to work, circuits, VD8, VD9 for the isolation diode to prevent VT3 deadline, due to the VT4 turn, makes the low collector potential VT3 two rows of lights are bright led, circuit VD1, VD2 diodes for the isolation of two oscillators.
  Circuit power supply with capacitor buck, buck capacitor voltage should be taken in more than 1µFCBB 400V capacitor, relay selection JQX-15, AC current up to its contact 20A, that can be used to control the air conditioning load, the machine Timing capacitor C1, C2 in the selection of electrolytic capacitors, be sure to use two anti-polar electrolytic capacitors in series, in order to prevent leakage work.
  Components Selection: IC1 use CD4069, IC2, IC3 are selected CD4017. VT1 ~ VT3 transistor 9013 are selected. X1 ~ X20 are selected F5mm red light emitting diodes. Relay selection JOX-15. Bulls used a commercially available socket card CN-109 Combination socket tin. Other components as shown.
  Production and commissioning: The machine in the production, the selection of a commercially available tin bull mix brand CN-109 socket, 4 socket will be relieved of them, leaving only two, and then relieved socket circuit board fixed in position , the original outlet in a 73mm × 76mm An organic panel, knob, switch, indicator light holes exposed, and panel stick to the case died, the original machine lights removed, its location just put the relay, the relay also fixed in the enclosure with plastic. Finally, when the relay machine connected to the outlet of the line should be selected sufficiently thick wire, and reliable connection, in order to avoid a large current through the load heat into the fire.