A Toy Tow Truck's Dome Light From Patio Lantern Circuitry

I have a relic of my boyhood that resides on a shelf -- a toy tow truck with a flashing dome light.

I've made some small improvements to it over the years, most notably to the switch that operates the dome light off the front axle's rotation.

The original switch was an unreliable affair, so I bypassed it with a microswitch. Here's a view of the truck's underside where the microswitch resides.

That microswitch arrangement worked out well, but the dome light itself wanted improvement. The original dome light was a No. 112^[1] incandescent bulb. The effect from it was lame. In operation, the bulb would barely get to incandescence before it got switched off again by the front axle's rotation. Some work that I'd done with solar patio lanterns led me to think that patio lantern circuitry might be applied to the problem to good effect.

I stripped down a patio lantern circuit board to its bare essentials, and installed it in the truck. I soldered the LED to the miniature screw base of a burnt-out light bulb, with the cathode connected to chassis ground. That turned out ok, and worked way better than the incandescent bulb ever did. Here's a view of the little circuit board residing inside the cab of the truck.

And here's a brief video of the dome light in action.

I know it's not great, but it's a big improvement over the incandescent.

Here's the schematic of the circuit.

Notes On The Schematic

• Diode D1 could be omitted altogether. I just left it in place to save myself the trouble of removing it.
• Pin 2 of the IC is the chip enable (CE) signal. That pin appears to be internally pulled down to the enabled state, so there was no need to ground the pin.

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Note:

[1] The No. 112 bulb is a TL3, miniature screw base, lens-end bulb rated at 1.2 volts, 220 milliamps.

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