A simple glow plug driver for model engines
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A glow plug driver
A simple and free glow plug driver to start model engines with methanol
type fuel (with castor or synthetic oil).
Designed by Stefan Spännare. Latest update 1998-04-08.
Oscilloscope view of signal:
Red: Voltage over glow plug. Blue: Voltage over 1 Ohm resistor.
Max current: 4.5 V / 1.0 Ohm = 4.5 A. Frequency 450 Hz.
- Very good glowing and starting properties.
- Works with all 1.5 V and 2 V glow plugs.
- The glow intensity of the glow plug can be adjusted with the potentiometer.
- Should be powered from a 12 V (starter) accumulator.
- Switched operation (low power consumption).
- Survives temporary glow plug short circuit.
- Survives reversed polarity.
- Very easy to build.
- Very cheap.
- The glow current can not be easily measured because of the switching.
Check the glow intensity with an unscrewed glow plug.
- Can not be used with normal small power supplies (only with accumulators)
due to high (5 A) transient currents.
- Be careful to not short circuit the accumulator when testing.
- The glow plug driver can easily be built on a normal laboration card.
- The function can be tested with a car lamp (12 V, 50 W) as "glow plug".
- The IC (NE 555) is a timer circuit, here used as switching oscillator.
- The transistor (BDX 34 C, Darlington) must have a small heatsink.
- The large diode must survive a current of at least 3 A on average.
- The LED (Light Emitting Diode) is of standard (20 mA) type.
- All resistors in Ohm or k Ohm (1 k means 1 kilo Ohm = 1000 Ohm).
- The potentiometer and small resistors must be of at least 0.25 W type.
- The 100 k Ohm potentiometer is of linear type.
- The large 1 Ohm resistor must survive 10 W (or at least more than 5 W).
- The capacitor is given in nF (nano Farad).
- The cables to the diod, transistor, 1 Ohm resistor and the glow plug
should be quite thick (0.75 mm²) due to high (5 A) transient currents.
Author: Stefan Spännare
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Latest update: 2006-03-12