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In many cases, the problem that usually arises is to install a timer in place and instead of an existing switch, that is to say a place where you only have two phases of the sector.
I - THE PRINCIPLE
The trick is to get on the power circuit of the bulb to control a dropping resistor of low value across which collected a few volts of alternating voltage. After recovery of the two alternations one has the direct potential required to operate the electronic assembly. The latter is reduced to a large capacity and counter based on adjustable-The end time of the timer is operated to cut off the supply to the lamp and therefore the self-supply of the timer. Two systems are available for controlling the supply of the bulb:
- The miniature relay.
This module has the advantage of completely isolate the control circuit of the power circuit. Small dimensions this circuit can be housed under the covers, in sealed boxes in plaster and intended to contain a conventional switch.
II - OPERATION
The red LED which the current is limited by resistance indicates that the installation is on.
To start the timer, simply press the push button which shunts or the relay contacts. At that time, food stands and self-maintained. She cut to the end of the timeout.
If the controlled power was more important, for example two bulbs 100 W.
The integrated circuit IC is a CD 4060. It is a binary counter of fourteen floors with built-in oscillator.
At the time of power assembly, the capacitor C2 is charged through R3, which results in a positive pulse on the reset input. The counter is thus automatically reset to zero.
Using a relay
The PNP transistor T comprises in its collector circuit of the winding of a relay 5 V (RT 1). As the Qi 4 output is low, the transistor T is saturated. Accordingly, the relay is closed. Its contacts operated that the lamp power. When the output Q14 goes high state timeout, the base-emitter current through Re continues. The transistor is blocked and the relay opens. The power of the bulb is stopped; it is the same to the electronic control circuit since there is more potential across the dropping resistor Ri. The diode protects the transistor T for the effects of overvoltage self manifested especially at the break. The relay used is a miniature relay 320R with a breaking capacity is 2 A.
III - THE REALIZATION
The Printed Circuit
Track configuration is not tightened. PCB copper epoxy. After etching in a bath of ferric chloride, all pellets will be drilled using a drill of 0.8 mm diameter. Some will expand to accommodate the diameter of the connections of larger components such as adjustable, the electrolytic capacity or terminal block.
The component layout
First, we will implement the resistances, supports Cl, capabilities and transistor. It will eventually adjustable, the rectifier bridge, the pushbutton, the LED, the relay or triac and the terminal block. The push button occupies the geometric center of the modules. One can thus use the plastic cover of a television antenna PNSE in which it is sufficient to adapt the central hole in the right diameter to allow the passage button. A second hole is to run for the signaling LED.
R1 : 10R / 3 W (bobinée)
R2 : 1 K (marron, noir, rouge)
R3 : 33 KR (orange, orange, orange)
R4 : 1 MR (marron, noir, vert)
R5 : 10 KR (marron, noir, orange)
R6 : 3,3 kR (orange, orange, rouge)
A : ajustable 220KR Horizontal
Pont de diodes 1,5 A
D : diode 1N4004
L : LED rouge 3mm
C1 : 1 000 MF/16V électrolytique
C2 : 22 MF/16 V électrolytique
C3 :0,1 MKT
T : transistor PNP 2N2907
IC : CD 4060
Support 16 brocbes
Relais 5 V/1 RT
Bouton-poussoir (pour circuit imprimé)
Bornier soudable 2 plots
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