The collector is connected to the tie point to the left of the base. The base lead in the middle connects to the orange link in the photo. The transistor is connected so that the emitter is to the right (the lead nearest the metal tab). Step 4: Insert a Wire Link Insert the 2N2222 Transistor (Q1) Step 3: Insert Resistor R2 (22kΩ) Insert a Wire LinkĬonnect a wire link from the negative terminal of C1 across the middle insulating channel. Step 2: Insert Resistor R1 (470Ω) Insert the 22k Resistor (R2)Ĭonnect R2 between the top rail and the negative terminal of C1. The other lead of R1 connects to the top rail of the breadboard which will be where the positive lead of the battery connects. R1 connects to the positive lead of C1, so connect it to a tie point in the same conductive strip of the breadboard. Step 1: Insert the Capacitor Insert the 470Ω Resistor (R1) The negative lead is marked on the body of the capacitor. In the photo the negative lead of the capacitor is on the right. The mapping of the NPN transistor symbol to the physical transistor in a TO-18 package is shown here: 2N2222, BC107, BC108 and BC109 NPN Transistor PinoutĪlternatively a PN2222 or KSP2222 transistor in a plastic TO-92 package can be used: PN2222 and KSP2222 NPN Transistor Pinoutīooks that may interest you: Building the Circuit Insert the 470uF Electrolytic Capacitor (C1)īend the longer (positive) lead of the capacitor out to the left and plug it into the breadboard so that there are 5 empty holes (tie points) between the two capacitor leads. make sure that the collector of the transistor is connected to the LED and not the base or emitter. Take care not to connect any of the transistor pins to the wrong part of the circuit - e.g. The transistor pinout needs to be observed - the collector (c), base (b) and emitter (e) of the physical transistor must be connected as shown in the circuit diagram.
We do not need to use an actual switch in the circuit, but can instead use a wire link to act as a switch by plugging it into the breadboard to close the switch or unplugging it to open the switch.
#USE TANK CIRCUIT AS TIMER SOFTWARE#
Notice that the value of R1 is 470R this is another way of writing 470Ω (or 470 ohms) and often appears in circuit diagrams where the software used to draw the circuit diagram does not have the capability to insert the ohm symbol. Be sure to place the correct value resistor in the correct place in the circuit.
ResistorsĪs you learned in tutorial 1, resistors can be connected with either lead to 9V. The polarity of the LED must also be observed - connect the LED the correct way around. The electrolytic capacitor must be connected the correct way around in the circuit - observe the capacitor's polarity. The positive terminal of the power supply (our 9V battery) must be connected to the +9V wire of the circuit diagram and the negative terminal of the power supply must be connected to the wire labelled 0V. The circuit shows that it is to be powered by 9V. In this way it is easy to find corresponding components on the circuit diagram and the circuit board. Circuit boards will typically have reference designators silk-screened on the board next to each component. They are also used to identify components on a circuit board. Reference designators allow easy reference to the circuit's components - e.g. A reference designator is the R1, R2, R3, D1, C1 and Q1 labels that you see. The circuit diagram differs from the circuit diagram of tutorial 1 in that the components now have reference designators assigned to them. Transistor Timer Circuit Diagram Reference Designators The circuit diagram for the simple transistor timer is shown below. The required parts are shown below: Transistor Timer Electronic Components Reading the Circuit Diagram You will need a breadboard, wire links, a 9V battery and the following components: QtyĤ70 ohm resistor (yellow - violet - brown)Īlso try the circuit with 1000uF and 100uF capacitors to see the timer's time period change Learn about capacitors, transistors and switches before starting this tutorial. You will need to have completed tutorial one where you would have learned about breadboards, resistors, LEDs and circuit diagrams.
#USE TANK CIRCUIT AS TIMER HOW TO#
How to build a slightly more complex breadboard circuit.