Transcript
6 Digit LED Educational Clock Kit This kit provides an opportunity for component recognition and soldering practice. Although not intended to be an everyday clock, it can certainly be used as such and you may wish to mount it into a clear plastic box.
The clock is designed to operate from an external regulated power supply providing 6 volts DC at 33mA, however, it will tolerate shortterm overloads up to 12 volts and it will operate at much reduced brightness down to around 4.5 volts - at which point it consumes only 10mA of current. If you have a power supply with switchable voltage output, you can experiment. Instead of a DC power supply, the clock will operate from a 4.5 volt or 6 volt lantern battery. If you use a DC power supply, it should be rated for 6 volts at 50mA or higher current (e.g. 100mA, 300mA or 500mA). If you use a 12 volt supply, connect the 180 Ohm resistor (supplied) in series with the positive lead to avoid overheating.
Clock Kit Instructions Page 1 © 2013 SatCure.co.uk
Assembly
If you are a beginner, the components may look bewildering but all will be explained. The Printed Circuit Board (PCB) is printed with the component designations. We recommend that you fit them in the following order: First, the 1N4148 diodes. They have a tubular glass body and a wire at each end. One end ("cathode") is marked with a black band. Bend the wires carefully and fit the diodes into the holes at the three locations labeled 1N4148. The black band end is marked by a stripe on the PCB. Bend the wires at 45 degrees underneath the PCB then solder them to the tinned copper pads. (It is assumed that you already practiced soldering or that you at least read our separate notes.) Snip (and keep) the wires off to leave about 1mm protruding from the solder. Take two of the wires that you snipped off, bend them and fit them to locations J1 and J2. Solder them and snip off the excess.
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Now locate the two 10K resistors. The coloured bands are difficult to read but the resistors are normally supplied on "bandoliers". For 10K the colours are Brown Black Black Red Brown. If in doubt, please check with a multimeter. Fit the 10K resistors in positions R8, R15. Resistors can be fitted either way round. Solder the wires and snip them off. Locate the six 4K7 resistors. The colours are Yellow Purple Black Brown Brown. Fit them at R9, R10, R11, R12, R13, R14. Solder the wires and snip them off. Locate the eight 470 Ohm resistors. The colours are Yellow Purple Black Black Brown. Fit them at R1, R2, R3, R4, R5, R6, R7, R16. Solder the wires and snip them off. Fit the I.C. Socket. Ensure that its notch is at the end marked on the PCB. Make sure that the socket is sitting flat on the PCB. Solder the pins. Solder the silver metal-cased crystal at location 12M next to the I.C. Socket. Solder the two brown disc capacitors printed "30" in locations labeled "30" next to the I.C. Socket. Solder the brown disc capacitor printed "104" in the location labeled "104" near the corner of the I.C. Socket. Fit the battery socket "BT1" in place. Solder the three LED display modules to locations DS1, DS2, DS3. Ensure that they are sitting flat on the PCB. The dot nearest the corner of each module should be next to to the dot printed on the PCB. The following parts should be pushed down until they are level with the tops of the LED display modules. Locate the black I.C. Printed "78L05" (which looks like a transistor) and solder it in position IC1, noting which way the flat surface is oriented according as the marking on the PCB.
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Solder the six transistors in positions Q1 to Q6, noting which way the flat surface is oriented according as the marking on the PCB. Look at the four red LEDs. Inside you can see an anvil shape that supports the light source. The wire connected to this anvil shape is the "anode" or "positive" connection. The other wire is the "cathode" or negative connection. The plastic moulding has a flat on its perimeter next to the cathode wire. The symbol is:Anode
Cathode
Insert each LED with its (flat) cathode side next to to the bar at the point of the triangle. Press down until it's level with the display modules then solder. Snip off wires. Take the electrolytic capacitor (tubular shape with two wires at one end) printed "220!F" and locate the negative wire marked by a stripe along the tubular body. The other wire is the positive (+) connection. Insert this capacitor at position C1 (which may be incorrectly labeled "100UF") making sure that the + wire goes into the hole labeled "+". Lie it flat on the PCB, solder the wires and snip off the excess. Likewise, take the three electrolytic capacitors labeled "10!F" and fit them in positions marked C2, C3, C4. Bend them over at 45°. Solder the screw terminal block in position "X1", ensuring that the entry holes are at the edge of the PCB. Solder the push-button switch in position "S1". Take the 20-pin I.C. and press one set of pins firmly against a flat surface. Press until they are at right-angles to the body of the I.C. Repeat with the other set of pins so that both rows of pins are now parallel. Insert the pins into the socket "IC2", ensuring that the notch of the I.C. Is at the same end as the notch in the socket this is the end furthest from the "IC2" marking on the PCB. Insert a 2032 battery cell into the "BT1" socket. Hold it at an angle so that the edge furthest from the "BT1" marking enters first. Press down until the cell clicks into place in the metal clip. The flat side should be uppermost. Clock Kit Instructions Page 4 © 2013 SatCure.co.uk
Operation Connect a 6 volt DC power supply to connector X1, observing correct polarity. Switch the power supply on. If the display doesn't light, press button "S1" briefly. If it still doesn't light, disconnect the power supply and check your work for mistakes. HOURS - MINUTES - SECONDS Hold S1 for two seconds then release. Either the hours or the minutes will flash. Repeatedly press S1 (briefly) and the number will count up. When it reaches the correct number, press and hold S1 for two seconds then repeatedly press S1 (briefly) and the other number will count up. Press and hold S1 for two seconds then release. The clock is now set. Note: The seconds display cannot be set. To switch the display off (standby) press S1 briefly. The clock will continue to keep time in this energy-saving mode. To turn the display back on, press S1 briefly. The PCB can be mounted on a clear panel or lid of a box by using bolts, nuts and spacer tubes 8 mm long. None of the components should be standing higher than the LED display modules, except for the screw terminal block. This can be filed down if required. A hole must be drilled for push button S1, which can then be operated by means of a matchstick or similar. Instead of a DC power supply, the clock will operate from a 4.5 volt or 6 volt lantern battery. The resistor colours may be thought to be unusual. However, the colour bands are normal for high-precision (1% tolerance) resistors. © 2013 www.SatCure.co.uk Other kits are available.
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