Battery crown charger by hand. How to make a crown charger

Diagram and description of a homemade automatic charger for charging 9 volt batteries (7D-01 “crown”) and the like.

The charger circuit is shown in Figure 1.

Click on the picture to view.

It consists of a half-wave rectifier on diode VD1, a voltage stabilizer on zener diode VD2 and ballast resistors R1, R2, an electronic switch on transistor VT1 and diode VD3, a threshold device on thyristor VS1.

While the battery connected to the XP2 connector is charging and the voltage on it is below the nominal value, the thyristor is closed. As soon as the voltage on the battery increases to the nominal value, the thyristor opens. The HL1 signal lamp lights up and at the same time the transistor closes. Battery charging stops.

The triggering threshold of the machine depends on the resistance of resistor R4.

Diode D226D can be replaced with any other from the same series, D226B - with another rectifier diode with a rectified current of at least 50 mA and a reverse voltage of at least 300 V, zener diode D813 - with zener diode D814D, transistor KT315B - with another transistor of this series with a current transfer coefficient of at least 50 , thyristor KU103V - thyristor KU103A.

Set up a homemade charger with a connected battery and a DC control voltmeter that measures the battery voltage. As soon as the voltage reaches 9.45 V, the warning light should flash. If this does not happen, then select resistor R4. The device is connected to the network only after the battery is securely connected!!!

Popular charger schemes:

Many people use standard 9V batteries (Krona) to set up or test many of their electronics projects. Of course, 9 volts are not always used - sometimes you need 5, 3 or even less, but it is either impossible or there is no desire to make up from lower-voltage batteries - after all, it’s easier to poke the crown and see how it will work there. And the excess voltage will simply sag due to the weakness of this galvanic element. But it’s better to do it correctly once - and then you won’t be afraid that something will go wrong on the diagram. Next, we suggest assembling miniature battery attachments - power supply boards. They provide the required reduced voltages and have a convenient form factor for use with a 9V battery.

On the printed circuit board there is a microcircuit - a regulator with wiring components on one side, and contacts for a 9 V battery on the other. In short, the idea is that the power supply will become part of the battery itself!

Several options for stabilizer circuits

This option uses a specialized buck converter:

The second version uses a buck/boost converter:

And this is a prototype that uses a cheap linear regulator LM317:

Printed circuit boards are etched, drilled (the radio components themselves are planar) and after desoldering, the board clings to the crown, providing the required voltage at the output.

Most radio amateurs use digital multimeters, which are powered by rechargeable batteries or Krona batteries.

At the same time, taking into account the law of meanness, they are always discharged at the most inopportune moment, when the performance of the entire project depends on the accuracy of measurements.

After visiting the store, I decided for myself that using a Krona battery is more economical than constantly buying and keeping a battery in stock. But this is only if the battery is used correctly.

Therefore, a simple charger was required. It can be purchased in many stores. BUT! Like many of you, I am not looking for easy ways. And it’s much more interesting and useful to come up with a scheme, assemble it, and set it up for high-quality work.

This is the charger I got.

This device allows you to charge Krona type batteries – 2 pcs. separate channels with optimal charging current (1/10 of the capacity) and has LED indication.

The indication consists of two LEDs. The 1st indicates that the battery is more than 50% discharged. 2nd – indicates that the battery is charged and can be removed from the device.

In addition, charging a discharged battery occurs in two stages: constant current charging and constant voltage charging.

Let's analyze the operation of the circuit. The circuit is powered by a constant (rectified) voltage from 12 to 30 V. But an increased supply voltage will cause a higher voltage difference across the LM317, which will lead to its heating and the need to install a heatsink. Therefore, I recommend powering the circuit with 12-15 V.

Turning on the LM317 in voltage stabilization mode allows you to obtain a constant (unchangeable) voltage at the output of the microcircuit when the supply voltage changes.

After LM317, a current stabilizer is made using two transistors. When we connect the terminals to a discharged battery, the voltage drop across the 27 ohm resistor significantly exceeds the opening threshold of the second transistor, which leads to the LED turning on and the first transistor partially closing and, thereby, limiting the charge current.

During the charging process of the battery, the voltage drop across the 27 ohm resistor at a certain moment closes the second transistor, which leads to an almost complete opening of the first transistor, which means that almost all of the input voltage goes to the emitter of the transistor, that is, to the output.

This ensures a safe charging current for the battery Krona.

The operational amplifier OP (LM358) acts as a comparator that monitors the voltage at the battery terminals and compares it with the installed variable resistor. As soon as the voltage exceeds the set value, the second LED will light up, indicating that the battery is charged.

We begin the setup by setting the output voltage. To do this, connect a voltmeter to the output terminals (without load) and use a trimmer resistor (in the LM317 stabilizer circuit) to set the voltage to 9.1-9.2V.

Next, to configure the operation of the LED, signaling the end of charging, we connect a voltmeter to the output terminals and connect the Krona battery. As soon as the voltage reaches 9V, rotating the trimming resistor (in the LM358 circuit) turns on the LED. This operation requires quite a lot of patience and precision, so I recommend using multi-turn resistors.

After adjustment, these resistors are covered with varnish or wax to eliminate the possibility of disrupting the previously made adjustment.

The board layout is made taking into account the available parts.

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05.06.2015

By and large, there are quite a few circuits of such chargers. This article presents a simple and cheap option that will help you make a charger for the Krona with savings and effort. The proposed circuit based on a cell phone charger allows you to make the device yourself.

The creator of the video is blogger Aka Kasyan.

By the way, a 9-volt battery is called Krona only in the Russian Federation and other countries that came from the USSR. It is known in the world as standard 6 f 22. Krona owes its name to a simple battery of the same standard, which was produced in the USSR.

You can find everything you need to assemble the device in this Chinese store. A plugin for Google Chrome to save money: 7 percent of purchases are returned to you. Please note products with free shipping.

The battery crown is an assembly of series-connected batteries, a rather rare 4a standard. In general, there are 7 of them. In most cases it is the nickel metal hydride type.

Charging schemes for battery Krona

It is recommended to charge the battery crown with a current of no more than 20 - 30 milliamps. It is recommended that you never increase the current above 40 milliamps. The charger circuit is quite simple and is based on a Chinese cell phone charger.

Inexpensive Chinese charger is not uncommon in two main types. Both, in most cases, are pulsed and implemented using self-oscillator circuits. The output provides a voltage of about 5 volts.

First type of charger

The first variety is the most popular. There is no control of the output voltage, but it can be changed by selecting a zener diode, which in most cases are in the input circuit in such circuits. The zener diode is much more common at 4.7 - 5.1 volts.

To charge the crown we need to have a voltage of about 10 volts. Based on this, we replace the zener diode with another one with the required voltage. In addition, it is recommended to replace the electrolytic capacitor at the output of the charger.

We replace it with 16 - 25 volts. Capacity from 47 to 220 microfarads.

Second type of charging

The second type - the circuit for charging cell phones is a self-oscillator circuit, but with control of the output voltage using an optocoupler and a zener diode. In such circuits, either a simple zener diode or an adjustable one, like tl431, may be used as a control element.

In this case, the simplest zener diode is 4.7 volts. The video demonstrates the conversion method based on circuit 2. First we remove everything that is present at the end of the transformer, not counting the output voltage control unit. This is an optocoupler, a zener diode and two resistors. We also replace the diode rectifier.

We replace the existing diode with fr107 (a good budget option).

In addition, we replace the output electrolyte with enormous voltage. We select a 10 volt zener diode. As a result, the charger began to output the voltage required for domestic purposes.

After completing the rework of the charger, we assemble a current stabilization unit based on the lm317 microcircuit.

In principle, for such insignificant currents it is possible to do without a microcircuit. Instead, put one quenching resistor, but preferably good stabilization. Still, the battery crown is not an inexpensive type of battery.

The stabilization current will depend on the resistance of resistor r1; download the calculation program for this microcircuit here.

This scheme works very easily. The LED will light up while the load is on at the output. In this case, Krona, because there is a voltage drop across resistor r2. As the battery charges, the current in the circuit will drop and at the same time the voltage drop across each resistor will be insufficient. LED o.

This will be at the end of the charging process, at a time when the voltage on the Krona is equal to the voltage at the output of the charger. Consequently, the upcoming charging process will become unfeasible. In other words, an almost involuntary principle.

You don’t have to worry about Krona, because the current at the end of the charging process is virtually zero. It is unnecessary to install the lm317t microcircuit on a radiator due to the scanty charging current. By and large it will not heat up.

In the end, all that remains is to attach a connector for the Crown to the output of the charger, which can be made from the second non-working Crown. And, of course, think about the housing for the device.

Charging for Krona from a dc-dc converter

If you pick up a small dc-dc converter board, you can make USB charging for the crown without any trouble. The converter module will increase the voltage of the USB port to the required 10-11 volts. And then along the circuit there is a current stabilizer on lm317 and that’s it.

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CROWN PHONE CHARGER. WITH YOUR OWN HANDS. DIY

Let's consider a device for charging low-power 9-volt batteries, type 15F8K. The circuit allows you to charge the battery with a constant current of about 12 mA, and when finished, it automatically turns off.

The charger has protection against short circuits in the load. The device is a simple current source, it additionally includes a reference voltage indicator on the LED and an automatic current shutdown circuit at the end of charging, which is made on a zener diode VD1, a voltage comparator on the op-amp and a switch on transistor VT1.

Schematic electrical diagram.

The level of charging current is set by resistor R7 according to the formula, which you can see in the original article in the picture (click to enlarge).

Operating principle of the charger

The voltage at the non-inverting input of the microcircuit is greater than the voltage at the inverting input. The output voltage of the operational amplifier is close to the supply voltage, transistor VT1 is open and a current of about 10 mA flows through the LED. When charging the battery, the voltage across it increases, which means the voltage at the inverting input also increases. As soon as it exceeds the voltage at the non-inverting input, the comparator will switch to another state, all transistors will close, the LED will go out and the battery will stop charging. The maximum voltage at which battery charging stops is set by resistor R2. To avoid unstable operation of the comparator in the dead zone, you can install a resistor, shown in the dashed line, with a resistance of 100 kOhm.

This circuit is well suited not only for conventional battery " Crowns", but also other types of batteries. You just need to select the resistance of resistor R7 and, if necessary, install a more powerful transistor VT3.

The finished memory can be placed in any plastic box of suitable size. Cases for non-working mobile phone chargers are also perfect. For example, one working, converted to a higher voltage, charging - a voltage source of 15V, and the other will contain circuit elements of the charger itself and contacts for connecting " Crowns"Assembling and testing the device: sterc

Discuss the article CHARGING THE 9V BATTERY CROWN

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