Adjustable electronic safety lock

of the Fig. 1

On fig. 2 is shown to img src by alt dependence of a current of operation of a safety lock on resistance of the R8 resistor. The type of this characteristic strongly depends on tension of opening of a trinistor.
Should be meant that at the supply voltage having considerable pulsations, the electronic safety lock works at tension peaks therefore the average current through loading will be slightly lower, than when using well maleficiated tension. the Current of operation of a safety lock it is possible to define br from expression: I _сраб =U _открVS1 / (R _экв +R8), where U _открVS1 - tension of opening of a trinistor, and R _экв - equivalent resistance of a chain of R3-R6 resistors. As shows the schedule on fig. 2, regulation of a current of operation by the R8 resistor in a zone of limiting values quite rough therefore expediently or to reduce limits of regulation by reduction of resistance of the R8 resistor in 1,5... 2 times or to enter multistage regulation by the switch with a set of precisely picked up resistors.
the Safety lock is mounted on the printed-circuit board from стеклотекстолита by thickness of 1,5 mm (fig. 3). On a payment all details, except the VT2 transistor, the R8 resistor and the SB1 button are placed. It is necessary to establish the VT2 transistor on a small heat-conducting path, for example, on a dural plate in the sizes of 90х35х2 mm with the unbent edges.
In the device it is possible to apply transistors and in the metal case, it is required to change a design and the sizes of a heat-conducting path only. It is possible to replace the KT817B transistor on Kt815b-KT815G, КТ817В, КТ817Г, КТ801А, КТ801Б, and КТ805АМ - on КТ802А, КТ805А, КТ805Б, КТ808А, Kt819b-KT819G. The static factor of transfer of a current of transistors should be not less than 45. Constant resistors - MLT, MT and MON; the variable resistor - any wire; the SB1 button - P2K without a clamp.
In a safety lock is better to use trinistor КУ103А with tension of opening 0,4... 0,6 Century the Collected safety lock of adjustment, as a rule, do not demand br. In certain cases it is required to pick up resistance of Rэкв addition of one more resistor for installation of the maximum current of operation. On a payment the place for four R3-R6 resistors is provided.
is simple to calculate a safety lock and on a bigger current of operation (to 3... 5 And). For this purpose more powerful transistors be required.

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of N ЭСАУЛОВ, settlement of Ivanovka, Voroshilovgrad Region, Radio No. 5, 1988 of, p. 31

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