Electronics. Page 2
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“DIY – with their own hands “- a site of interesting handmade crafts, made from improvised materials and items at home. Step by step master classes with photos and descriptions, technology, tips – everything you need for handicrafts true craftsman or just a handyman. Crafts of any complexity, a wide range of directions and ideas for creativity.
Three useful circuits for the garage and not only
In this article, let’s look at three circuits of medium complexity that can be used for a variety of purposes and will be very useful not only for the garage. A Simple Circuit Breaker with Remote Control
can be made on the basis of the decimal decoder cd4017, such a switch can be controlled by any infrared remote control of the TV, DVD player, etc.
The scheme rotates on foreign sites since 2011, the original source unfortunately could not be found, but one thing is clear, the option of such a switch is quite popular and can be found almost on every site.
The counter has 10 outputs, after supplying power to the first output of the chip, which is the contact at number three, we have a high signal or the logical unit. According to the schematic there is a LED connected to this pin which will light up as soon as we feed power to the circuit.
The infrared signal from the remote control is received by the receiver, usually at the output of such a receiver is a logical one or a high-level signal if it does not lend itself to the infrared signal and a logical zero if the receiver receives a signal.
A signal in this case I call infrared radiation from the remote control, the output of the receiver is connected to the base of the bipolar transistor with direct conduction.
If there is no infrared signal the transistor is closed, if there is a signal it is triggered, through its open junction the plus from the power supply goes to the counter input and the one is switched to the second output or pin number two.
In this case, triggered the second transistor, through its open junction receives power to the winding of the relay and the latter is triggered switches the load, when you press again any button on the remote unit switch to the third output or pin number four, the transistor closes, the load turns off.
The fourth pin of the microcircuit in turn is connected to the reset pin of the counter, so the counting will start again, the corresponding LED will light up.
About the infrared receiver
The pin assignment may be different, therefore it is recommended to find the datasheet and study it. The receiver can be taken from non working household appliances with infrared remote control.
The relay is selected with a coil voltage of 5 volts, you can use and 12 volt relays, in this case, the control circuit must be powered from a step-down stabilizer for 5-6 volts, and the input circuit to supply 12 volts…
SECOND circuit was developed by me on the basis of the first option, this switch can control three different loads, in fact it is already a switch. We have 4 modes of operation.
The first pressing – on pin 2 appears one and the high level signal opens the first transistor, triggers the first – switching the load, for example a light bulb.
The second press – the one from pin 2 is switched to the fourth. The first relay is disconnected and the second relay is triggered, activating the second lamp, the same happens with the next pressing and triggers 3 relays, the fourth pressing one appears on pin 10 and through the diode isolator this one goes to the bases of all three transistors, which leads to simultaneous operation of all three relays and all the lamps are lit.
Subsequent pressing of the button leads to disconnection of all loads, because the next output is connected to the reset terminal of the counter and the counting starts from 0, i.e. 1 appears on terminal 3 and the cycle repeats.
The 5 volt relays are also used in this version, you can replace them with 12 volt relays in the same way as in the case of the first circuit.
The printed circuit boards are always available for download at the end of the article.
Both circuit boards do not have relays but I think it is very easy to connect them because the boards have detailed signatures and protection diodes for the control transistors.
The third option is more functional, it is convenient to use in large garages in which several sources of light, such a switch will allow you to activate the lighting in the area of the garage where you work.
Of course the switch can be used to activate various loads, electric heating, lighting and so on, it all depends on your imagination.
The scheme can be controlled from almost any remote control at a distance of up to 10 meters, the power of the connected load depends solely on the bandwidth of the relay.
Both circuits work even with 50 percent variation in the ratings of the components used, transistors virtually any low-power corresponding conductivity. No problems should arise with the search for components, circuits work immediately after power supply and requires no additional adjustment, if, of course, everything is assembled correctly.
Therefore I recommend to assemble them on printed circuit boards from the archive.
The THIRD circuit will protect the appliances from surges in the mains voltage, in this scheme, we again used electromagnetic relay, this time 12-volt.
In order to galvanically isolate the low-voltage control circuit of the mains part, a low-power, step-down transformer was used.
The secondary of the transformer must provide a voltage of 9-12 volts at a current of 150 to 300 milliamps, that is, a transformer is needed with a capacity of about 2 – 3 watts, you can and larger, but there is no point.
If the mains voltage rises to an unacceptable level, the stabilitron triggers, which leads to the death of the transistor and triggers the relay. And the load, which is connected to the network through the protection circuit instantly turns off.
The circuit is adjusted by turning the trimmer resistor. First we need a regulated source of alternating voltage.
Applying a voltage of 250 volts to the protection circuit and turning the trimmer until the relay does not trip, this completes the setup. Increasing the line voltage, increases the voltage on the secondary side of our transformer, consequently the supply voltage to the control circuit also increases. If it is higher than the set threshold, the stabilizing diodes will trip and what was mentioned at the beginning will happen.
Now it is time to test our circuit. A small light bulb is connected as a load and a multimeter shows the mains voltage.
As you can see everything works, this circuit can be built into an extension cord or into a separate box and you are welcome to use it. Again, I will note that the power of the connected load depends on the allowable current through the relay contacts.
Reinforce the tracks on the circuit board with solder if you are going to connect high power loads to the circuit.
I strongly recommend adding a fuse to the circuit, the current of the fuse should be chosen according to your load. For example, if you plan to connect to the scheme of loads with a power up to 1 kilowatt, the fuse must be taken at about 6 amps, the relay in this case should be designed for a current of at least 10 amps. Double current reserve is a guarantee of reliable operation of the circuit.
At the end, I remind you that you must be extremely careful when working with mains voltage, during the adjustment, I advise you to disconnect the device from the mains and use rubber gloves.