What does the project present?
The vintage DIY electronic kit presented extends the service life of nickel cadmium (NiCd) watch batteries, whose voltage did not fall below 70% of the nominal voltage value of 1.5V, by their periodic regeneration, once every few months.
An integrated circuit of original design is used in the assembly - BU 1011 known as the alarm generator. It was designed and manufactured at IPRS Baneasa, in order to provide a unitary solution for the construction of electronic surveillance and warning systems, automation that requires opto-acoustic warning systems, security, anti-theft protection.
How does the assembly work?
Although BU1011 it has no terminal-to-terminal compatible equivalent, there are other similar integrated circuits on the component market such as block diagram and field of application. One such circuit is the LM 1801 - National Semiconductor - produced for applications that use smoke detectors. Another circuit in the family of alarm generators, specially designed for fluid detectors is LM 1830.
In Figure 1 the block diagram of the circuit is presented, which highlights the following blocks:
1. The alarm block which includes:
- a voltage reference with internally polarized Zenner dione;
- voltage comparator CP1;
- voltage comparator CP2, with one of the inputs connected to the voltage reference;
- logic for mixing the comparator outputs with an SI-OR function;
2. AO operational amplifier;
3. INV inverter motor.
In most applications with the help of the comparator CP1 an oscillator is made that can transmit intermediate signals at the output of the alarm block. The oscillation frequency can be fixed from outside the circuit, with the group of components R2, R1, C1.
comparison CP2 allows the passage of oscillations to the output (alarm generation) only if the voltage on terminal 15 is lower than the voltage reference.
The alarm can also be triggered independently of the state of the comparators CP1, CP2, by applying a voltage more than 1V on the terminal 12 of the integrated circuit.
To better understand the operation of the integrated circuit BU 1011, we have attached below the catalog data:
The assembly presented in Figure 2 performs battery regeneration at a constant current (100uA) and interrupts the battery supply when the voltage at its terminals exceeds 1.5V. In this way battery regeneration is done unattended, without the risk of damaging it.
During charging, the LED lights up continuously, and at the end of charging it goes out. In the absence of a battery or when its terminals are not well contacted the LED flashes. The block diagram of the assembly is given in Figure 3.
Battery power it is made from the output of the alarm block (terminal 7) by means of the variable resistor RV2 with the help of which the value of the charging current can be adjusted.
The AO operational amplifier is in hysteresis comparator configuration. The voltage at the battery terminals is compared with a reference voltage, fixed on the resistive divider R1 + RV1 and R2. When the battery potential exceeds the reference value, the output of the operational amplifier switches, applying a voltage of almost 0V on the output of the logic gate OR. The logic gate locks and shuts off the battery. Diode D5 prevents the battery from discharging through RV2 + R5, R4 and LED after charging is interrupted.
When the battery is not connected in the circuit, the assembly works as a relaxation generator: the capacitor C6 is charged through the group RV2 + R5, D5 and is discharged through the input of the operational amplifier (which absorbs a current of 2..3uA).
In the electronic scheme (figure 2) the variable resistor RV1 has the role of fixing the maximum voltage applied to the battery in the range 1.5 - 1.55V. The value of the charging current is adjusted with the help of the variable resistor RV2 in the range 100..120uA. The assembly can be supplied both in direct current from a 10-15V voltage supply and in alternating current from the 8-10V, 50Hz bell transformer.
Technical characteristics of the assembly:
- Supply voltage: 8-10Vac / 10-15Vdc
- Output voltage: minimum 1.5V
- Regeneration current: min. 0.1 mA
- Current absorbed by the source: max. 18 mA
List of required components (with recent equivalents):
- IC1 - integrated circuit BU1011 (because it has no pin-to-pin compatible equivalent, the assembly can be adapted using LM 1801 or LM 1830)
- D1 - D5 - rectifier diodes - 1N4007
- D6 - red LED
- C1 - C4 - 3.3nF capacitor
- C5 - capacitor 220uF / 25V
- C6 - capacitor 4.7uF / 40V
- R1 - 33k resistor (min 0.25W)
- R2 - 10k resistor (min 0.25W)
- R3 - 470k resistor (min 0.25W)
- R4 - resistor 1k - 1.2k (min 0.25W)
- R5 - resistor - 15k (min 0.25W)
- R6 - resistor - 47k (min 0.25W)
- RV1 - semi-adjustable 25k
- RV2 - semi-adjustable 100k
- Printed wiring or breadboard test board
- Tin or connecting threads
Download the original IPRS leaflet Baneasa 8606
Because the integrated circuit B1011 it is no longer manufactured and has no pine-to-pine equivalent on the market, you will most likely find it at collectors or at vintage electronics enthusiasts. If you manage to buy it, we have attached its internal scheme to better understand its functionality.
Below I have attached pictures with the assembled product. Of course, today the assembly may have a smaller size.
Many of you are probably wondering how this DIY electronic kit was packaged or distributed. Below I have attached some pictures with packaged product (new) and the contents of the envelope. Thank you Mr. Marius Balauta for providing pictures.
Also, thanks Mr. Romulus Mihai for providing pictures with catalog data for the integrated circuit BU1011 from the book "Radu Rapeanu / Leonard Sarbu - 30 practical applications of the integrated circuit BU1011, Technical Publishing House 1985".