The difficulty in repairing is not usually the repair itself, but having the necessary tools to carry it out. A clear example is the tuning of the ignition, for which, if we do not have a stroboscopic gun, the task becomes difficult, or we must resort to someone who can do it “by ear.”
Here we will learn how to make a stroboscopic pistol, that although it will not be something of professional use, works perfectly and can be used to fine-tune any vehicle with a 4-stroke engine with spark ignition.
– Lamp for strobe flash of Xenon with “U” shape
– Transformer 6V + 6V 1A
– 2 transistors 2N3055
– 1 bridge rectifier 1000V 1.5A (W10)
– Capacitors: 1x 1mF 400V; 1x 100nF 100V; 2x 22nF 63V; all of Polyester
– Resistors: 2x 220W 1W; 1x 1MW ¼W
– Fuse holder and 5A fuse
– Virgin plate of 10cm x 4cm
– 2 crocodiles for battery
– 17cm x 6cm fibrofacil wood base
– Accessories for mounting, such as 3mm screws, plastic spacers, cables, turned pins, etc. …
Below you can see the schematic circuit:
The operating principle of the Xenon flash is as follows: these work with a voltage between 300V to 600V, but just applying said voltage is not enough; the lamp must be “fired,” ionizing the Xenon gas, so that it becomes conductive and current flows. This is done using a short pulse of 1000V or more.
This circuit consists of two stages.
The oscillating stage, by which the pair of transistors 2N3055 transform the 12V of direct current into alternating current and apply it on the secondary winding of a 6 + 6V transformer.
The second stage rectifies the high voltage delivered by the primary of the transformer, converting it to direct current again, but this time they are not 12V, but more than 500V !!!. Be very careful, because if you touch the high voltage parts with your fingers, it can hurt a lot.
As you can see, there is no “firing” stage of the lamp, so when you connect the circuit, nothing will happen. The voltage needed to trigger the flash will be obtained from the ignition system of the car, more precisely, the high voltage wire of the spark plug corresponding to cylinder No. 1.
proceed to draw the tracks on the virgin plate.
You have to draw them as you see in the figure, you do not have to invert them or mirror them. To give an idea of the scale, take as reference the mounting holes of the 2N3055 transistors. The idea is not to draw the tracks like this, but then “fill” the blanks, so that the clues are thicker.
To give you an idea of what I am saying, look at a picture of how I am staying:
Here you can see the image of how they have to assemble the components. The pin + of the Xenon flash corresponds to the one with a red mark. If there is no red marker on any pin, another way to identify them is by looking at the electrodes: the negative electrode has a filament similar to that of incandescent lamps, and the positive electrode has a metal plate only.
As you may have noticed, the 2N3055 transistors are fastened with 3mm screws, but these screws do not fulfill that unique function, but they are also the collector pin of the transistor, so make sure that the nut makes good contact with the copper tracks of the plate.
This is how the armed plate is:
For the final assembly, it does not make much sense to buy a cabinet, since it would be more expensive than the circuit. It can be mounted on a fibro facil plate as shown in the figure:
From the secondary of the transformer, only the two end cables are connected to the plate; the midpoint goes directly to + 12V (previously passing through the 5A fuse).
Then connect a bipolar cable to the earth terminal of the board, and the other to the fuse terminal. At the ends of this cable, crocodiles can be placed to connect easily to the battery of the car.
To capture the high voltage necessary to trigger the flash, a direct connection to the 1st cylinder cable will not be used since the voltage delivered by the coil is very high (more than 15,000V) and can damage the flash.
The connection will be made in a “capacitive” way, winding some cable around the high voltage cable of the 1st cylinder. This cable is the one connected to the HV terminal of the board.
And here you can see the circuit running:
They may prefer to test it well before using it in the car, for that they will need an external source that provides a voltage peak of more than 1000V to be able to fire the lamp. This mysterious source of high voltage can be a Magiclick or any other spark.
One more thing … the flash of the Xenon lamps emit a lot of ultraviolet light, which is harmful to the eyes. Do not look directly into the light while using the flash.