- Fri Mar 31, 2017 7:22 pm
#64466
The second circuit works ok for lower power devices but the current draw of the ESP8266 is a lot higher than the ATMEGA328. You need to be able to supply the peak currents. The supercap can help with this but it really isn't a good design. This circuit wastes power that could go into charging a battery. But since a battery is not included in the design it doesn't matter if that power is thrown away.
The first circuit will not operate as low as a PNP based circuit, the basis of many low drop regulators. The emitter follower circuit (as shown) is what you will find in a lot of regulators that are not LDO. The semiconductor manufactures actually know their stuff and if you think you can get better results with that circuit it just means that you have not taken a good look at what a properly designed regulator is capable of.
Freecanadian wrote:I am more excited to have found a couple of circuits showing it may be possible to use a Zener diode, a resistor, a capacitor, and an NPN transistor or possibly a Mosfet to build a simple voltage regulator. I plan to try this method, since it seems this circuit can clip the voltage down to spec (based on Zener selected) but also allow lower voltage to flow thru as the battery discharges. The circuit I tested with a simulator showed 0.7v drop with NPN transistor, 5.5v input and 3.3v output at 300 ma, and was based on this circuit: http://electronics.stackexchange.com/qu ... o-nrf24l01
Nick Gammon also used a simpler zener circuit to regulate the charging voltage to the super-cap in his solar powered AtMega328 page: http://www.gammon.com.au/forum/?id=12821
The second circuit works ok for lower power devices but the current draw of the ESP8266 is a lot higher than the ATMEGA328. You need to be able to supply the peak currents. The supercap can help with this but it really isn't a good design. This circuit wastes power that could go into charging a battery. But since a battery is not included in the design it doesn't matter if that power is thrown away.
The first circuit will not operate as low as a PNP based circuit, the basis of many low drop regulators. The emitter follower circuit (as shown) is what you will find in a lot of regulators that are not LDO. The semiconductor manufactures actually know their stuff and if you think you can get better results with that circuit it just means that you have not taken a good look at what a properly designed regulator is capable of.
