How to make a strobe with your own hands. LED stroboscope
Owners of carburetor vehicles are familiar with the difficulties of the ignition adjustment process. This is usually done by ear, which is not very convenient. Using a stroboscope, this process can be facilitated. However, industrial devices are quite expensive, so many people make a stroboscope for ignition with their own hands.
The drawbacks of industrial models
Industrial devices often have certain disadvantages, due to which the usefulness of the device is very doubtful.
For a start, the price of them is quite substantial. For example, modern digital models will cost a car enthusiast 1000 p. More functional models are already from 1700. Advanced strobes are about 5500 p. Needless to say, a car strobe (made with its own hands) will cost a car driver 100-200 rubles.
Often in the factory devices, the manufacturer uses a particularly expensive discharge lamp. The lamp has a certain resource, and after a while it will have to be replaced.And this in itself is equivalent to the acquisition of a new factory unit.
Why is it worth making a strobe yourself?
The disadvantages of factory and technologically advanced devices push the motorist to independently manufacture this device. In addition, it is much cheaper to equip this equipment with LEDs instead of an expensive lamp. An ordinary laser pointer or flashlight will be suitable as a source of diodes or a donor.
The remaining items will also cost a penny. Special tools are not needed. The budget of the strobe manufacturing process will be no more than 100 rubles.
How to make a strobe with your own hands?
Schemes and options for manufacturing there is a huge amount. However, for the most part all projects for creating this gadget are similar. Let's see what it takes to build.
We will need a simple transistor KT315. It can easily be found in the old Soviet receiver. The designation may be slightly different, but it does not matter. Thyristor KU112A can be easily obtained from the power supply of a vintage TV. You can also find resistors of small sizes.Since we are doing the LED strobe with your own hands, then naturally you will need an LED flashlight. For this, it is better to buy the cheapest one from China. In addition, you need to stock up on a capacitor to 16 V with any low-frequency diode, a small 12 A relay, wires, crocodiles, a shielded wire 0.5 m long, and a small piece of copper wire.
We assemble the device
The scheme is small, and you can place it right in the very Chinese lantern. So, through the hole in the flashlight behind it is desirable to skip the wires to power the device. At the ends of the wires is better to solder the crocodiles. It is necessary to make a hole in the side wall if the Chinese have not already made it. A shielded wire will be laid through this hole. At the back end, it is necessary to insulate the sheath and solder the same piece of copper wire to the main conductor of the wire. It will be a sensor.
Device layout and operation principle
After applying current through the power supply wires, the capacitor charges very quickly through a resistor. When a certain charge threshold is reached, the voltage across the resistor will flow to the opening contact of the transistor. Here the relay will work.When the relay closes, it will create a circuit of a thyristor, an LED and a capacitor. Then, through the divider, the impulse gets to the control output of the thyristor. Then the thyristor opens, and the capacitor is discharged to the LEDs. As a result, the stroboscope, self-made, flashes brightly.
Through a resistor and thyristor, the base terminal of the transistor is connected to the common wire. Because of this, the transistor closes and the relay turns off. The glow time of the LEDs increases as the contact does not break immediately. But the contact will break, and the thyristor will be de-energized. The circuit will return to its base position until a new impulse arrives.
By changing the capacitance of the capacitor, you can change the glow time. If you choose a larger capacitor, the LED strobe, made by hand, will be brighter and glow longer.
The device on the chip
The main part of this simple circuit is a chip type DD1. This is the so-called one-shot 155AG1. In this scheme, it starts only from negative impulses. The control signal goes to the transistor KT315, and it will form these negative pulses. Resistors 150 K ОМ, 1 К ОМ, 10 К ОМ, as well as КС139 Zener diode work as limiters of the amplitude of the input signal from auto ignition.
A 0.1 mF capacitor with a resistance of 20 KΩ will set the desired pulse duration, which will be formed by the microcircuit. With this capacitor capacitance, the pulse duration will be up to about 2 ms.
Then, from the 6th leg of the microcircuit, the pulses, which by this moment will be synchronized with the ignition of the machine, will go to the base terminal of the CT 829 transistor. It is here as the key. The result is a pulsed current through the LEDs.
How is this strobe powered for cars? We need to do a couple of wires to the car battery terminals. It is necessary to monitor the level of battery charge.
If you correctly assemble this simple circuit, you can immediately see how the device works. If suddenly the brightness is not enough, then this is regulated by the selection of the appropriate resistance.
As the case for the device, you can use the old or Chinese flashlight.
Another strobe circuit
This stroboscope on LEDs, made by own hands by this principle, can also be powered from a car battery. Diodes will allow you to create protection against incorrect polarity.As a fastener is used here a common crocodile. It must be attached to the high-voltage contact of the first spark plug on the motor. Next, the pulse passes through the resistors and the capacitor and comes to the input of the trigger. By that time, this input will already be switched on by a single vibrator.
Before the pulse, the one-shot is in normal mode. Direct trigger output is low. Inverse input, respectively - high. A capacitor connected to the inverse of the plus will be charged through a resistor.
A high-level pulse triggers a one-shot, which switches the trigger and serves to charge the capacitor through a resistor. After 15 ms, the capacitor is fully charged, and the trigger switches to normal mode.
As a result, the one-shot will respond to this with a synchronous sequence of rectangular pulses with a duration of about 15 ms. The duration can be adjusted by replacing the resistor and capacitor.
The pulses of the second chip are up to 1.5 ms. For this period, open transistors, which are an electronic switch. Then a current flows through the LEDs. According to this principle, the stroboscope for the car works (it was made or not with its own hands, it does not matter - both devices shine the same).
The current passing through the LEDs is much greater than the passport. But, since the flashes are short-lived, the LEDs will not fail. Brightness will be enough to use this useful device even in the daytime.
This strobe can be assembled with your own hands in the case of the same long-suffering flashlight.
How to work with the device?
By assembling the device according to one of the above diagrams, you can simply and easily, and most importantly, precisely tune the ignition on carburetor engines, check the correct operation of the plugs and coils, and monitor the operation of the timing angle regulators.
In order to expose the ignition as correctly as possible, it is usually assumed that the mixture ignites a couple of degrees before the piston reaches the highest point. This angle is called the "lead angle". When the crankshaft revs increase, the angle must also increase. So, this angle is set at idle, and then it is necessary to check the correctness of the settings in all modes of operation of the unit.
We expose the ignition
We start and warm up the engine. Now we power our strobe LED and connect the sensor.Now you need to send the device to the mark on the timing case and find the mark on the flywheel. If the moment is broken, the labels will be far enough from each other. By rotating the timing case, make sure the tags match. When you find this position, fix the timer.
Then it's time to raise the momentum. The tags will diverge, but this is quite a normal situation. This is how the ignition setting is carried out using a strobe light.
So, we figured out how to make a strobe LED with their own hands.