Capacitive power supply with zener diode

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Marcel DaJanchar

Joined Sep 9, 2015
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Hello!

Recently, I have made a lot of small projects, which include MCU (ATTINY13a) with some inputs (reading frequencies, digital signals) and sometimes outputs (LEDs, output BJT). As far as projects being successful, I am wondering, why is this type of power supply nowhere to be found on the web? Everyone seems to be using linear regulators such as LM7805 for that kind of projects. Well probably I just don't know the right keywords to find it.

I have attached my power supply schematics, which is working fine. Can you give me some cons and pros for ''my'' power supply and linear regulators? I am aware that this power supply will not handle much current. Also, which one is preffered for this kind of projects and why? Most of my projects are used in automotive. Does this kind of power supply produce a lot of noise for other electronics attached to same ground line (if more than 5 power supplies of this type are used in the same car)? I have also attached simple project for frequency detection (so you see where this power supply is being used as example).

Thanks in advance!
 
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dl324

Joined Mar 30, 2015
16,913
Try searching for "zener voltage regulator".

If you study voltage regulating circuits, you'll find that they start with a resistive voltage divider, then proceed to a zener regulated circuit. The next step would be a linear regulator that is superior to the prior circuits.
 

dendad

Joined Feb 20, 2016
4,476
A linear regulator will be more efficient than a Zener supply. Using a Zenner, the current is always the maximum, whereas a liner reg will only supply the current needed (plus the regulator quiescent current). As you say, the Zener supply you are using is low current, so if it is working ok, just use it.
If you need better regulation or more current, then a linear reg may work better. And the old 7805 regs are ok, but there are many around now that have lower quiescent current and better voltage regulation.
For higher currents still, a switch mode reg dissipated a lot less power.
 

DickCappels

Joined Aug 21, 2008
10,169
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