The memory has protection against short circuit in the load. The device is the simplest 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 the VD1 zener diode, the voltage comparator on the op-amp and the key on the VT1 transistor.
Schematic diagram.
The level of the charging current is set by the resistor R7 according to the formula, which you can see in the original article in the picture (click to enlarge).
The principle of operation of the charger
The voltage at the non-inverting input of the microcircuit is greater than the voltage at the inverting one. Output voltage the operational amplifier is close to the supply voltage, the transistor VT1 is open and a current of about 10 mA flows through the LED. When the battery is charging, the voltage on it increases, which means that 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 turn off and the battery will stop charging. The voltage limit at which the battery stops charging is set by resistor R2. To avoid unstable operation of the comparator in the dead zone, you can install a resistor, shown by a dashed line, with a resistance of 100 kOhm.
Instruction
Familiarize yourself with the pinout of the Krona battery. For the battery itself or this type of accumulator, as well as for the power supply that replaces it, the large terminal is negative, the small terminal is positive. For a charger, as well as for any device powered by Krona, the opposite is true: the small terminal is negative, the large terminal is positive.
Make sure the battery you have is actually rechargeable.
Determine the charging current of the battery. To do this, divide its capacity, expressed in milliamp-hours, by 10. You get the charging current in milliamps. For example, for a 125 mAh battery, the charging current is 12.5 mA.
As a power source for the charger, use any power supply whose output voltage is about 15 V, and the maximum allowable current consumption does not exceed the charging current of the battery.
Check out the LM317T stabilizer pinout. If you put it face down with the marking towards you, and the pins down, then there will be an adjusting pin on the left, an exit in the middle, and an entrance on the right. Install the microcircuit on a heat sink, which is isolated from any other current-carrying parts of the charger, since it is electrically connected to the output of the stabilizer.
The LM317T chip is a voltage regulator. To use it for other purposes - as a current stabilizer - turn on a load resistor between its output and the control output. Calculate its resistance according to Ohm's law, given that the voltage at the output of the stabilizer is 1.25 V. To do this, substitute the charging current, expressed in milliamps, into the following formula:
R=1.25/I
The resistance is in kiloohms. For example, for a charging current of 12.5 mA, the calculation would be as follows:
I=12.5mA=0.0125A
R=1.25/0.0125=100 Ohm
Calculate the power of the resistor in watts by multiplying the voltage drop across it, equal to 1.25 V, by the charging current, also previously converted to amperes. Round the result up to the nearest value from standard range.
Connect the plus of the power source to the plus of the battery, the minus of the battery to the input of the stabilizer, the adjusting output of the stabilizer to the minus of the power source. Connect a 100 uF, 25 V electrolytic capacitor between the input and the control terminal of the stabilizer, plus to the input. Shunt it with ceramic of any capacity.
Turn on the power supply and let the battery charge for 15 hours.
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Batteries "Krona" appeared in the Soviet Union, but still remain in demand. This battery is indispensable for devices with high energy consumption, as it produces a current of much greater strength compared to other batteries.
Characteristics of batteries "Krona"
Batteries are types AA, AAA, C, D, they have a cylindrical shape and differ only in size. Unlike them, the Krona battery has a PP3 size and is a parallelepiped. Salt batteries are distinguished by their fragility, they cannot be used in high-tech devices. The maximum that they are designed for is a watch or other simple device. Batteries are also distinguished by the electrochemical system. Alkaline and lithium batteries are more efficient.
Krona mini-batteries are distinguished by a fairly high performance, they have an output voltage of around nine (in comparison with it, a lithium or alkaline AA battery “gives out” only 1.5 volts). The Krona battery consists of six one and a half volt batteries connected in series in one chain (the output is nine volts.) The batteries can have a current of up to 1200 mA / h, the standard power is 625 mA / h. The capacity of Krona batteries will vary depending on the types of chemical elements. Nickel-cadmium cells have a capacity of 50 mAh, nickel-metal hydride batteries are an order of magnitude more powerful (175-300 mAh). Lithium-ion cells have the largest capacity, their power is 350-700 mAh. Standard size batteries "Krona" - 48.5x26.5x17.5 mm. These batteries are used in children's toys and control panels, they can be found in navigators, in shockers.
How to charge the battery "Krona"
In the Soviet Union, carbon-manganese batteries of this size were produced, as well as alkaline batteries, which had a higher price and were called "Korund". Batteries were produced from rectangular biscuit elements; for their manufacture, a metal case made of tin-plated sheet, a bottom made of plastic or genitax, and a contact pad were used. Simple disposable Krona batteries allowed a small number of recharges, although this was not recommended by the manufacturer. However, due to the deficiency of these nutrients, many books and magazines have published
Consider a low-power 9-volt battery charger, such as the 15F8K. The circuit allows you to charge the battery with a constant current of about 12 mA, and at the end it automatically turns off.
The memory has protection against short circuit in the load. The device is the simplest 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 the VD1 zener diode, the voltage comparator on the op-amp and the key on the VT1 transistor.
Schematic diagram.
The level of the charging current is set by the resistor R7 according to the formula, which you can see in the original article in the picture (click to enlarge).
The principle of operation of the charger
The voltage at the non-inverting input of the microcircuit is greater than the voltage at the inverting one. The output voltage of the operational amplifier is close to the supply voltage, the transistor VT1 is open and a current of about 10 mA flows through the LED. When the battery is charging, the voltage on it increases, which means that 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 turn off and the battery will stop charging. The voltage limit at which the battery stops charging is set by resistor R2. To avoid unstable operation of the comparator in the dead zone, you can install a resistor, shown by a 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 choose the resistance of the resistor R7 and, if necessary, put more powerful transistor VT3.
The finished memory can be placed in any plastic box that is suitable in size. Cases from non-working mobile phone chargers are also great. For example, one working, converted to increased voltage, charging is a 15V voltage source, and in another there will be circuit elements of the charger itself and contacts for connecting " crowns". Assembly and testing of the device: sterc
Discuss the article CHARGING THE BATTERY CROWN 9V
Today, the krone battery is used in many electronic devices. This battery is produced by almost all battery companies. On the shelves of stores, a crown battery from different manufacturers can be found.
In this article, you will find out which companies produce this energy source, how to charge it, what is the cost of the product, what it consists of and much more!
What is a crown?
Krona is a rectangular 9-volt battery with two poles on one of its ends. This element was created back in the Soviet Union, but is still popular. May be referred to as PP3.
Is the crown a battery or an accumulator?
Initially, this element was produced as a simple battery. But with the development of technology, they began to produce rechargeable batteries of the Krona type. Therefore, there are both battery crowns and conventional ones. At the time of purchase, it is advisable to ask the seller what kind of energy source it is. You can also ask the question: "How many times can you recharge?".
On some of these batteries, everything is already written.
The picture shows that it can be charged as much as 1000 times. But the usual crown is only 2 times. After that, it may fail. Manufacturers do not recommend charging it.
battery crown photo
Below are 6 pictures of 9v power supply.
Well, this is exactly what the crown battery looks like.
Why is a battery called a crown?
It is problematic to answer this question precisely, but it can be assumed that this is due to her appearance. The crown is usually called the top of the trees or a coin. And from here you can give an answer as the crown battery is called, more precisely from where it takes its name.
The top two poles can be compared to the top branches of trees. There is a consonant word crown. Perhaps the name of this battery takes from this word. Because it vaguely resembles this item.
Among the many schemes for assembling chargers for batteries of the "Krona" type, there was a relatively simple and affordable one. By the way, a 9-volt battery, known in Russia and the CIS countries as "Krona", has a 6F22 standard.
The battery consists of 7 4A nickel-metal hydride batteries connected in series. The recommended current for charging is no more than 20-30 mA.
Charger is made by reworking a Chinese-made mobile phone charger.
There are 2 types of inexpensive chargers originally from China. They are pulsed, and both are based on self-oscillating circuits capable of delivering 5 V at the output.
The first type is the most common. It does not have output voltage control, but by selecting a zener diode, which is in such circuits in the input circuit near the 1N4148 diode, you can get the desired voltage. Usually it is of two types - at 4.7 and 5.1 V.
To charge the Krona, a voltage of the order of 10-11 V is needed. This can be achieved by replacing the zener diode with one that has the appropriate voltage. It is also recommended to change the capacitor, which is located at the charging output. As a rule, it is 10 V. You need to put a 16-25 V capacitor with a capacity of 47-220 microfarads.
The second type of such circuits has output voltage control, implemented by installing an optocoupler and a zener diode.
Take a look at the principle of reworking the second circuit.
It is necessary to remove all components after the transformer, and leave only the node that controls the voltage at the output. This node consists of an optocoupler, a pair of resistors and a zener diode.
It is necessary to replace the diode rectifier, since the manufacturers claim a charging current of 500 mA, and the maximum diode current is not more than 200 mA, although the peak current is about 450 mA. It's dangerous! In general, you need to install the diode FR107. Thus, charging will produce the required voltage.
The next thing to do is to assemble the current stabilization unit, based on the LM317 chip. In general, you can get by with one quenching resistor instead of assembling a stabilization unit.
But in this example, preference is given to reliable stabilization, because the Krona-type battery is not the cheapest.
Resistor R1 affects the stabilization current. The calculation program can be downloaded in the Attached files, at the end of the article.
The principle of operation of this scheme is as follows:
When the "Krona" is connected, the LED lights up.
A voltage drop is created across resistor R2. Gradually, the current in the circuit decreases, and the voltage that allows the LED to burn becomes insufficient at one moment. It simply fades away.
This happens at the end of the charging process, when the battery voltage becomes equal to the charger voltage. The charging process stops and the current drops to almost zero.
The LM317 chip is not required to be installed on the radiator, unlike, because the charge current is very meager.
It remains to attach a battery connector to the case, which can be made from a non-working battery.
If you use a DC-DC converter, you get a charger for Krona via a USB port. similar to this.
Attached files: .
Soldering the plug to the shielded audio cable Universal protection for batteries
