An adjustable fixed present generator is an important device for a lot of digital purposes, particularly when a steady present is required whatever the load. This undertaking, designed and constructed with a PIC16F1765 microcontroller, combines each fixed present sourcing and sinking capabilities in a single gadget, with the flexibility to regulate the worth from 0 to 1000 mA.
Key options embody fixed present technology, present sinking functionality, an built-in timer with mAh calculation, computerized shutdown when no present is flowing, and calibration. The timer is especially helpful for charging NiMH batteries, enabling exact present software for set intervals.
The unit is managed by way of three buttons (UP, DOWN, ENTER), with visible suggestions supplied by an SSD1306 show. An elective ammeter might be added for calibration functions. The system is powered by an exterior 5 V provide able to delivering as much as 1 A.
On the coronary heart of the system is the PIC16F1765, chosen for its onboard 10-bit ADC and DAC, in addition to an built-in operational amplifier able to instantly driving a BD137 transistor in an emitter follower configuration. This permits for exact and steady present management. A essential challenge throughout growth was noise generated on the I²C bus by the SSD1306 module, resolved by supplying each the show and the PIC with 3.3 V by way of an LP2950 regulator, eliminating knowledge corruption issues.
Meeting might be achieved on a breadboard, with parts cut up throughout two boards to suit the chosen enclosure: one internet hosting the microcontroller and show, the opposite the BD137 transistor, the 1 Ω energy resistor, and relays. It’s important to mount a warmth sink on the BD137 to forestall overheating.
The firmware, written within the JAL programming language, handles the consumer interface, shops settings in non-volatile reminiscence, and controls the present with updates each millisecond. Utilizing Excessive Endurance Flash (HEF) ensures long-term reliability. Crimson and blue LEDs point out supply and sink modes respectively.
In demonstration, the gadget performs duties similar to calibration to 1 A, charging batteries at 200 mA, discharging at 400 mA, computerized shutdown, and capability calculation. This can be a sensible, versatile undertaking, ultimate for makers and electronics professionals who want a compact, adjustable device for testing and lab purposes.
