Post your questions and comments about this article to the Controlling Motors Message Board. Orders can also be placed by telephoning Rapid on 01206 751 166 or visiting their website at Prices quoted include VAT at 20%.īookmark or Share This Article Confused? Order the above items from Rapid Electronics via our Circuits Shop and help support the Electronics in Meccano website, without affecting the price you pay! Just click on an item for information about it and/or to add it to your Rapid order. Partģ8mm Heatsink for TO220 Style Transistor Cases The list below includes all the parts required to build the Darlington pair circuit on stripboard as shown in figure 2. The article below describes another version of the Darlington pair circuit which reduces the voltage loss to 0.7V. Connect up a power power supply and test the circuit.Connect a motor between the Output and 0V.The other two terminals may be connected either way On a potentiometer (shown in figure 2 by the line with the arrow) is normally Connect a potentiometer to the circuit as shown.If the heat sink shorts outĪny of the tracks, cut them at an appropriate place to avoid this. Cut the copper tracks where an X is shown.Fit the TIP31C transistor with the B leg at the top, such that the legend on.Fit your chosen heat sink - this must be done before you fit the TIP31C.Soldering time to a minimum for this component. This 'heat shunt' will prevent the heatįrom your soldering iron damaging the transistor. Place a crocodile clip around each leg of Resistor and 1N4148 diode, taking care to place the diode the correct way To drill holes of the appropriate size and in the appropriate position for Somewhere within the right-hand rectangle, you will also need If you wish to fit a 6-way screw terminal block, use a 1.5mm diameter drillīit to enlarge the six holes in the stripboard shown within the left-hand.Cut a piece of stripboard to 11 tracks x 18 columns + extra columns if the.Not shown for they will depend on the nature of the heat sink you choose. Stripboard layout for a heat sink, but the positions and sizes of the holes are List, or you could make one out of Meccano! Space is provided in the To it to dissipate the heat - a suggested heat sink is given in the Shopping The TIP31C transistor will get hot in use because the highĬurrent supplying the motor flows through it. Pin-out diagrams of the two transistors used in this circuit are given inįigure 3. Supply voltage may be 60V and the maximum motor current consumption may be 3A. With the TIP31C transistor given, the maximum power The power supply for this circuit should preferably be un-smoothed (i.e.ĭirectly from the power supply rectifier). Includes space for an optional 6-way screw terminal block to make connecting up This circuit can also be used to control other devices - it could be used asĪ stripboard layout for this circuit is given in figure 2. Potentiometer will be more subtle in the middle of its range.īecause a motor is an inductive load, it will produce a 'back-emf' whichĬould damage the second transistor. Not absolutely linear so the change in motor speed for a given rotation of the There are, however, a couple of disadvantages of this simple circuit.įirstly, about 0.7V is lost in each transistor, so the maximum voltage that canĮver be applied to the motor is Vs - 1.4V. Transistor, and then again by the second transistor, greatly increasing theĪmount of current that can be controlled by the potentiometer. The current from the potentiometer is amplified by the first The small amount of current flowing out of the potentiometer's wiper isĪmplified by two transistors, connected together in a configuration known as a Such that the voltage at its wiper terminal will always be somewhere at or The circuit in figure 1 shows a linear potentiometer connected between Vs and 0V Transistors - This article is not yet available This allows a low powerĬircuit to control a higher power circuit, either in an on/off fashion or linearly. 'collector' terminal to its 'emitter' terminal. Its 'base' terminal to control the amount of current flowing from its The job of a transistor is to allow the small amount of current that enters ThisĪmplification can be achieved using transistors. Potentiometer can pass can be amplified into order to run the motor. Instead, the small amount of current that the Of a motor since motors draw large amounts of current which would burn out Take a look at my new MECControl project at Ī normal potentiometer (variable resistor) cannot directly control the speed
DARLINGTON TRANSISTOR WINDOWS
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