The use of an integral timer for automatic voltage control when charging batteries. Scheme, description

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The use of an integral timer for automatic voltage control when charging batteries. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Chargers, batteries, galvanic cells

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Based on the type 555 integral timer, an automatic battery charger can be assembled. The purpose of such a charger is to maintain a fully charged backup battery to power a measuring device. This battery always remains connected to AC power, whether it is currently being used to power the device or not. The integrated timer automatic charger uses both comparators, a logic flip-flop, and a powerful output amplifier.

The reference zener diode D1, using an internal resistive divider in the timer IC, supplies reference voltages to both comparators. The voltage at the output of the timer (pin 3) switches between 0 and 10 V.

The use of an integral timer for automatic voltage control when charging batteries

When calibrating the circuit, instead of a nickel-cadmium battery, an adjustable DC voltage source is included. The "Off" potentiometer is set to the desired final charging voltage of the battery (typically 1,4 V per cell), the "On" potentiometer is set to the desired initial charging voltage (typically 1,3 V per cell).

Resistor R1 limits the operating current of the circuit to less than 200mA under all conditions. Diode D2 prevents the battery from discharging through the timer when the latter is in the "off" state. The capacitor serves to block oscillations during the transition of the circuit to the "off" state. If required, the feedback divider can be decoupled by capacitance to improve the noise immunity of the circuit during transients.

Author: N. McGowan; Publication: N. Bolshakov, rf.atnn.ru

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The rotation of Mars is accelerating every year 26.08.2023

Thanks to radio signals from NASA's InSight lander, we can track the rotation of Mars. The analysis showed that its speed is slowly growing.

The growth in circulation remained unknown until the research team found evidence of acceleration using the RISE instrument, designed to study the planet's internal structure. Previously, he helped determine that the core of Mars is most likely a ball of molten metal.

The growth in circulation remained unknown until the research team found evidence of acceleration using the RISE instrument, designed to study the planet's internal structure. Previously, he helped determine that the core of Mars is most likely a ball of molten metal.

Examining RISE data from InSight's first 900 days on Mars, they saw that the planet's rotation was accelerating by 0,76 milliseconds for every Earth year. Martian days are gradually getting shorter. But why?

RISE's main goal was to see how much Mars wobbles as its orbit is attracted and repelled by the sun's gravity. This would make it possible to determine whether the core is solid or liquid. However, RISE was also tasked with measuring the length of the Martian epoch. A day on Mars is slightly longer than on Earth - 24 hours 37 minutes. RISE measured the rotation speed and wobble of Mars using reflected radio waves. When it received a radio signal from NASA's Deep Space Network (DSN), it reflected those waves back to Earth. The difference between the frequency of the signal sent by the DSN and the signal reflected back to Earth told the InSight team how the craft moved with Mars. Changes in the frequency of the reflected radio waves indicated both orbital fluctuations and how long a day lasts on the Red Planet.

But while we know why Earth's rotation slows down over billions of years and makes our days longer, scientists are not sure of the exact reason why Mars' rotation is speeding up and its days are getting shorter.

One theory suggests that this is due to changes in the planet's ice caps. Carbon dioxide from the atmosphere condenses at the poles as the planet cools in the fall and winter and sublimates during the warmer months of spring and summer. Such fluctuations constantly shift the center of mass of Mars. when the ice goes away, it comes back again.

In addition, researchers believe that Mars may be accelerating due to a core-mantle coupling involving the transfer of momentum from the liquid core to the mantle.

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