Penlight Meter Backlight and Voltage Mismatch Light Hacks

• 0:00 Penlight Meter Backlight Hack Attempt: Modifying an a3005a penlight meter to always have the backlight on was attempted, however, it failed.

• 0:11 Initial Goal: To enable the backlight permanently, considering the recipient's preference and battery life concerns.

• 1:11 Current Draw Measurement: Turning on the meter draws 1.3mA; enabling the backlight increases it tenfold.

• 1:51 Resistance Testing: A resistance box was used to dim the backlight and reduce current draw, finding a suitable balance at 10k ohms (0.6mA increase).

• 3:15 Discovery of Always-On Drawback: The chosen method would continuously drain the battery, even when the meter is off.

• 3:36 Hack Failure: Due to the circuit design (emitter connected directly to ground), the backlight modification wasn't feasible without constant battery drain.

• 4:18 Light Hack: Modifying 220V lamps to work at 110V

• 4:18 Initial Problem: The creator received 220V lamps instead of the ordered 110V ones.

• 4:47 Internal Analysis: Examined the lamp's circuitry for voltage conversion possibilities.

• 5:55 Circuit Board Overview: The circuit includes a bridge rectifier, linear current sink chips (SM 1082 DS), and LEDs arranged in series-parallel configurations.

• 6:21 SM 1082 DS IC: Linear current sink IC's that limit the current to the LED's

• 7:08 Modification Strategy: Cutting traces and using jumper wires to rewire the LEDs in a different parallel configuration to reduce the voltage required.

• 7:44 Voltage Measurement: The voltage across each diode series was measured to be around 9.7 volts.

• 8:04 Rewiring for 110V: Cut traces, paralleled LED sections, and removed a current-limiting resistor to reduce the LED current to 12.5mA.

• 8:54 Testing and Success: After the modfication the lamps now draw 50mA and the hack was a sucess.

• 9:11 Grounding: Successfully grounded the case for safety by bringing the ground to the metal screw.

• 9:21 Hack Outcome: Despite the penlight backlight modification failing, the lamp hack was successful.