Hi. I have a 12V PSU which I want to reduce to 4V 2A PSU. I have used a NPN power transistor (BD137) plus a 270Ω resistor and a 5V zener to make a regulator which gives me a 4.4V output which is still too high.
Is it a good idea for me to just put a silicon rectifier of some sort in series with the regulator output to give me a further 0.6V drop thus giving me a 3.8 V regulated output?
Would that be reliable?
Ideally I should use a 4.6V zener which I can't get.
I have used a NPN power transistor (BD137) plus a 270Ω resistor and a 5V zener to make a regulator which gives me a 4.4V output which is still too high.
Either use a real adjustable voltage regulator circuit (involving at least a second transistor) or a combination of zener and rectifier diodes that best fits 4.6 V. 4.7V is a standard zener voltage, by the way. Not to mention voltage regulator ICs...
Either use a real adjustable voltage regulator circuit (involving at least a second transistor) or a combination of zener and rectifier diodes that best fits 4.6 V. 4.7V is a standard zener voltage, by the way. Not to mention voltage regulator ICs...