Chloroplast type 1 SE

Description: The MC34164 voltage regulator used in the Chloroplast SE differs from the 1381 voltage regulator utilized in the VTSE and 1381 SEs in that the MC34164 features an "open drain" output, necessitating a pull-up resistor connected to the positive supply for the output to achieve a high voltage. The Chloroplast SE incorporates a resistor in series with the MC34164 chip input, leveraging the characteristic that the quiescent supply current for the MC34164 is elevated when the output is low and nearly zero when the output is high. Consequently, the voltage drop across the series input resistor, produced by the quiescent current of the MC34164, must be factored into the rated "turn-on" voltage, increasing the voltage required on the supply capacitor to activate the MC34164 (i.e., to 7V). Once the MC34164 is activated, the quiescent current falls to zero, resulting in no voltage drop across the series resistor, which causes the voltage at the MC34164 input pin to suddenly rise to the supply capacitor voltage. The "open" output pin of the MC34164 is then pulled up to the supply through the output resistor, but the output voltage only reaches the forward voltage of the Darlington transistor base-emitter junction, approximately 1.2V. The Darlington transistor activates, allowing current to flow to the rest of the circuit. The supply capacitor voltage begins to decline as the motor load depletes the capacitor charge until the supply voltage falls to the rated turn-off voltage of the MC34164 (i.e., 5V), at which point the cycle restarts. In a previous design of the MC34164 hysteresis SE (hySE), the upper threshold was increased by placing a resistor in the ground lead and utilizing the voltage drop generated by the quiescent current, while also sinking current from the output pull-up resistor. Craig Maynard significantly improved this design by simplifying the circuit in his innovative Chloroplast design. A common misconception regarding the Chloroplast SE is that it offers a stable regulated 5V supply for powering microcontrollers; in reality, it provides a fluctuating supply voltage with a minimum lower level set to 5V. This design choice is typical, as most latching or timed SEs can accommodate this feature. Another hybrid SE is introduced, integrating the principles of the Miller Engine with the Chloroplast SE. Two configurations are presented: the upper one employs a Darlington transistor, while the lower utilizes two separate NPN transistors, which exhibit a lower "on" voltage and deliver slightly more power to the motor. Both Chloroplast SE versions trigger at 4.8V and reset after a duration determined by capacitor C2. The primary storage capacitor, C1, can range from 10,000µF to 1F, while the timing capacitor, C2, can vary from 1µF to 100µF. A prototype of the lower schematic was tested near the 49th parallel, where, with C1 set to 10,000µF and C2 to 100µF, the trigger point was established at 4.8V, resulting in a cycle time of approximately 20 seconds under overcast conditions and about 2.5 seconds in bright sunlight. The efficient Mightymo gearmotor achieves around four rotations per second.

The MC34164 voltage regulator operates in a unique manner due to its open-drain output configuration, which requires careful consideration in circuit design. The necessity of a pull-up resistor ensures that the output can transition to a high state only when the voltage is adequately supplied. This design choice impacts the overall efficiency and responsiveness of the circuit, particularly in applications such as solar-powered systems where variable light conditions can influence performance.

The series resistor connected to the MC34164 input plays a critical role in determining the activation threshold of the regulator. By understanding the relationship between quiescent current and voltage drop across the resistor, designers can optimize the supply capacitor's voltage rating to ensure reliable operation. The interaction between the Darlington transistor and the MC34164 output further enhances the functionality of the circuit, allowing for effective current delivery to the load while managing voltage levels.

The hybrid SE design exemplifies innovation in energy management, combining established principles with modern enhancements to create a versatile solution. The ability to adjust the timing and storage capacitor values allows for fine-tuning of the circuit's performance, accommodating various operational requirements. This adaptability is particularly beneficial in renewable energy applications, where efficiency and responsiveness to environmental conditions are paramount.

In conclusion, the MC34164-based Chloroplast SE represents a sophisticated approach to voltage regulation and energy management, demonstrating how thoughtful circuit design can yield significant improvements in performance and efficiency. The integration of various components and the careful consideration of voltage thresholds and current flows exemplify the complexities involved in modern electronic circuit design.The MC34164 VS used in the Chloroplast SE is different in one respect from the 1381 VS (used in the VTSE and 1381 SEs) in that the MC34164 has an "open drain" output which requires a pull up resistor to the positive supply for the output to go positive. The CSE uses a resistor in series with the 34164 chip input and takes advantage of the fact tha t the quiescent supply current for the 34164 is higher when the output is low and decreases to almost zero when the output is high. That means the voltage drop across that series input resistor, generated by the quiescent 34164 current, must be added to the rated "turn on" voltage which raises the voltage on the supply cap required to turn on the 34164 (ie to 7V).

After the 34164 turns on, the quiscent 34164 current drops to zero and the voltage drop across the series resistor also drops to zero, so that the voltage at the 34164 input pin suddenly jumps up to the supply cap voltage. The voltage at the "open" 34164 output pin is now pulled up to the supply through the output resistor, but the output pin voltage only rises to the forward voltage of the darlington transistor base emitter junction or about 1.

2V. The darlington turns on and the collector supplies current to the rest of the circuit. The supply cap voltage starts to drop as the motor load etc depletes the cap charge until the supply voltage reaches the 34164 rated turn off voltage (ie 5V) and the process repeats In one of my earlier MC34164 hysteresis SE designs (hySE), the 34164 upper threshold was raised by inserting a resistor in the ground lead and using the voltage drop generated from quiesent current and sinking the current from the output pull up resistor. Craig Maynard greatly improved on that design using the same principle but simplifying the circuit in his elegant Chloroplast design.

One popular misconception about these the Chloroplast SE is that it provides a convenient regulated 5V supply for powering up micros etc when in fact all it provides is a fluctuating supply voltage whose lower level can be set to 5V minimum. This is just a matter of design choice since all but the simplest latching or timed SEs offer this possibility.

Here is a yet another hybrid SE, this time combining the principle of the Miller Engine with the Chloroplast SE. Two versions are shown with the top one using a Darlington transistor and the bottom using 2 separate NPN transistor s which have a lower "on" voltage and deliver slightly more power to the motor.

Both MS Chloroplast SE trigger at 4. 8V and reset after a time determined by C2. The value of the main storage cap C1 can be 10, 000uF to 1F and the value of timing C2 can be 1uF to 100uF. My prototype of the lower schematic sits in the window near the 49th parallel and with C1=10, 000uF and C2=100uF, the trigger point is 4.

8V and the cycle time was about 20 sec with yesterday`s overcast sky and about 2. 5 seconds in this morning`s glorious sunshine. The efficient mightymo gearmotor turns about 4 rotations in 1 second.