Universal Cronizador
By means of this circuit we will be able to disconnect any electrical device after a period of predetermined time.
In the figure the diagram of the same is appraised in which if it operates on the S1 key (S11 abre and S12 closes) the capacitores C1 and C2 is loaded through the diodes D1 and D2, respectively, causing to an increase of tension on C2 the one that is applied to the floodgate of triac Q4, happening this one to the conduction state.
The tension on C2 also is applied to the elements that determine the time of the circuit which they are R8 and C4. The tension on these two elements is regulated by means of the R3 potentiometer, having thus been able to regulate the time of the circuit.
| List of components | |||
| Resistance (0.5 W 10%) | Capacitores | Semiconductors | Several |
|
- R1, R5 - 100 ohms - R2 - 150k ohms - R3 - Potentiometer 10 k ohms, linear - R4 - 1k ohms - R6 - 3k ohms, 5 W - R7 - 390 ohms - R8 - 4,7M ohms - R9 - 5.6 ohms - R10 - 3,9k ohms - R11 - 150 ohms - R12, R13 - 470 ohms |
- C1, C2 - 10uF, 200 V, electrolytic - C3 - 50uF, 15 V, electrolytic - C4 - 4uF - C5, C6 - 0,01uF 25 V or more, 10% |
- D1, D2 - rectifying Diodes RCA SK3030. - Q1 - Transistor of effect of field MOS, 3N139 - Q2 - Transistor RCA SK3005 - Q3 - Transistor RCA SK3020 - Q4 - Triac RCA 40503 or RCA 40429 |
- F1 - Fuse of dependant value with the load (máx. 5A) - S1 - Key handle, bipolar, double. |
Note of design:
If triac RCA 40429 is used, a heat dissipater will be due to use.
The R6 resistance generates heat and therefore it will have to be avoided that it is near other components.
The determining elements of the time are R8 and C4, these elements and their associate connections will have to be prote'ge's of the accumulation of earth and dirt, since this one can cause alternative ways for the leakage current, affecting this way the determination of the time of the circuit.
If a greater rank of times to the available one by means of the use of the R3 potentiometer is desired, a selective key can be used that allows to exchange several values for R8 and C4. It is necessary to consider that C4 does not have to be electrolytic and in addition R8 will not have to surpass the 100 Ms ohms.
In order to obtain the maximum period obtained with the combination R8 and C4 (in seconds) the value of both will be due to multiply (R8 in ohms and C4 in uF) and of dividing it per 1,59
