Sized 200 Uf Timing Capacitor. the Sche- Delay Time

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Sized 200 Uf Timing Capacitor. the Sche- Delay Time

fit your needs. It was 100,000 -ohms in the author's model giving him a minimum time HOUR MASTER delay of 30 seconds. Capacitor Cl may also be changed in value to modify the sized 200 uF timing capacitor. The sche- delay time. With a 200 uF capacitor and matic shows how it's done. Diac D1 and a 10 megohm pot, the maximum delay is Triac Q3 form a standard AC phase con- well over an hour and over a half -hour trol which can be turned off through the with a 5 megohm pot. contacts of relay K1. For use as a speed Getting Busy. The author's model was control, R4, a 250,000 -ohm linear pot, is housed in a 61/4 -in. x 33ús -in. x 17A3 -in. added as shown to points A and B. With plastic case with an aluminum panel used mode switch S3 in the out position. you as the top plate of the unit. You may have a regular speed control. When battery want to start by drilling holes in the cover switch S2 is closed, the timing circuit is for switches, pot(s), and socket. Be sure t armed. By pressing time -start switch S1, to add an extra hole for potentiometer R4 timing capacitor Cl is charged by the bat- if you want the speed control feature. tery; when Si is released, Cl slowly dis- Go to work on the circuit board; you charges through time -set pot R1 and can use about a 2 -in. x 41/2 -in. piece of source -follower Q1. perforated phenolic board. Wiring is Time-set potentiometer R 1 can be either straight -forward, but keep the triac 5 or 10 megohms. Resistor Rx sets the low circuitry and the FET at opposite ends of limit of the timer and may be selected to (Continued on page 93) unmuumnmuunnmunmummummuuuuummuunmuwumnuuuummmuwunmuuuuuumuuummuuuuumuummuummumimmwuuuuuuuuumnnunumuumuum PARTS LIST FOR HOUR MASTER B1 -9 -volt battery, Eveready 216 or equiv. Rl -5 megohm to 10 megohm, linear taper po- C1 -1 to 1000 uF, 12 -VDC electrolytic capacitor tentiometer (see text) (see text) R2- 2,700 -ohm. 1/2-watt resistor, 10% C2 -0.05 uf, 600V disc capacitor R3- 120,000 -ohm, 'h -watt resistor, 10% (see C3-0.1 uF, 600V disc capacitor text) D1 -Diac, Motorola HEP -31 1 S1 -SPDT pushbutton switch (Switchcraft 1002 Kl -Sensitive SPDT relay (Potter & Brumfield or equiv.) (time -start switch) type 1M5 or equiv.) (see text) S2 -SPST toggle switch (power switch) 01-N- channel FET, Motorola HEP -801 S3 -SPDT toggle switch (mode switch) Q2 -NPN transistor, Motorola HEP -55 5O1 -AC receptacle, chassis mount Q3- Triac, RCA 40429 Misc.- Hardware, knobs, perforated board, flee Rx- 100,000 -ohm, 1/2-watt resistor, 10% clips, wire, solder, etc. MODE ,BI 52 SWITCH R4 if = OUT 9VDC ÓFF-ONON 250K TIME START (PUSH BUTTON) al g SI HEP -801 (SEE CI TEXT) 200uF RX (SEE TEXT) NOTE: e b c g TI REMOVE JUMPER SOI BETWEEN A B B T2 AND INSERT R4 (CASE) FOR SPEED CASE CONTROL /LAMP DIMMER MODIFICATION. HEP -801 HEP-55 40429 mmnummummuunuuuuuummiinmmnmmpnunnuunmuuumuuuuuwuuuumuwmuummuunqu+ mununuummuuunumuuununmuuumuumumuuuuuuunuuuwr. 58 ELEMENTARY ELECTRONICS .

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Thyristors.Pdf
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Teccor® brand Thyristors AN1001 Fundamental Characteristics of Thyristors The connections between the two transistors trigger Introduction the occurrence of regenerative action when a proper The Thyristor family of semiconductors consists of several gate signal is applied to the base of the NPN transistor. very useful devices. The most widely used of this family Normal leakage current is so low that the combined hFE are silicon controlled rectifiers (SCRs), Triacs, SIDACs, and of the specially coupled two-transistor feedback amplifier DIACs. In many applications these devices perform key is less than unity, thus keeping the circuit in an off-state functions and are real assets in meeting environmental, condition. A momentary positive pulse applied to the gate speed, and reliability specifications which their electro- biases the NPN transistor into conduction which, in turn, mechanical counterparts cannot fulfill. biases the PNP transistor into conduction. The effective hFE momentarily becomes greater than unity so that the This application note presents the basic fundamentals specially coupled transistors saturate. Once saturated, of SCR, Triac, SIDAC, and DIAC Thyristors so the user current through the transistors is enough to keep the understands how they differ in characteristics and combined hFE greater than unity. The circuit remains “on” parameters from their electro-mechanical counterparts. until it is “turned off” by reducing the anode-to-cathode Also, Thyristor terminology is defined. current (IT) so that the combined hFE is less than unity and regeneration ceases. This threshold anode current is the holding current of the SCR. SCR Geometric Construction Basic Operation Figure AN1001.3 shows cross-sectional views of an SCR Figure AN1001.1 shows the simple block construction of an chip and illustrations of current flow and junction biasing in SCR.
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