DN1• 12
1. Identify and install DPDT switch S2. Be sure to push the switches flat
to the circuit board. Solder all six connections.
2. Install the other DPDT toggle power switch S3. Once again, be sure to
push the component flush to the circuit board before soldering.
We’ll start our “learn-as-you build” instructions with the power supply section
of the circuit.
3. Install the 2.5 mm power connector in the J3 position.
4. Install D6, a 1N4002 type diode. Notice that one end of this
component is marked with a band. Diodes are “polarized”, that is, like a
battery, they have a positive (+) and negative (-) side. Be
sure to follow the parts diagram carefully and orient the
banded end as shown. Note also that this component will
“stand up” in place. Form the component leads as shown
before installing the part.
5. In the same manner, install diode D5, 1N4002 type. Be
sure to orient it correctly! See the parts diagram for correct
placement.
Diodes D5 and D6 act as circuit “protection”. If the power is hooked up
incorrectly D6 acts as an “open circuit” to prevent damage to the voltage
regulator and the charger IC. Diode D5 prevents the battery pack under
charge from powering the unit if the input power is accidentally removed.
6. Install C5, 10 uF electrolytic capacitor. Electrolytic capacitors are
polarized with a (+) and a (-) lead and must be installed in the correct
orientation. Ordinarily, only the negative side is marked on the capacitor
body with a dark band and the (-) sign clearly shown, while PC boards
will usually show the (+) hole location. Use care to ensure proper
polarity. See the parts diagram for proper placement.
7. Install C6, 10 uF electrolytic capacitor. Watch the orientation! See the
parts diagram for proper placement.
8. Identify VR1, the 78L05 voltage regulator (marked 7805). This device
produces a stable 5 volt reference for the circuit. Notice that this
component has a “flat” side with the writing imprinted on it. Be sure to
place the part as shown in the parts diagram.
9. Install C2, 10 uF electrolytic.Observe the correct polarity! If installed
incorrectly, this component can heat up and even explode!
That wasn’t so bad, now was it! You have just completed the power section
of your DN1. Take a moment now to recheck your solder connections and
touch up any less than perfect connections. Have a second look at the
component polarities in this section as the majority of these components
have a (+) and (-) orientation.
10. Install R3, 470 ohm [yellow-violet-brown].