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I need a PRO's opinion on this circuit please

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Most low voltage DC adapters that have an output current as low as only 100mA are pretty bad.
I have a cheap 9V/100mA adapter that gets hot even without a load then its voltage is 20V. With a load of 100mA its average voltage is 9V with lots of ripple.

Maybe you can buy a half-decent adapter and hope that the manufacturer does nor cheapen it during your purchase of many of them.
 
Ok,

So if I keep a 9V reg and then use a voltage divider like this would it make more sense?
power2.jpg
5V will control a PIC, 2 LEDs and a piezo.

Mike
 
The two resistors produce 5.0V only when they have no load. The 5V will drop when there is a load. It will probably drop so low that the PIC, LEDs and piezo will not work.
 
So I guess I don't have a choice but to use two regulators!
Unless I can be sure I get a batch of 9V or 12V wall-wart that are identical and remove the 9V reg...?
Do I have any other choices? My only concern is cost. (Without affecting my circuit's proper operation)
 
A zener diode and a resistor may be a good enough 'regulator' for the 9V stuff and might be cheaper than a regulator. Then you could use any wall wart of suitably high voltage.
 
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So I guess I don't have a choice but to use two regulators!
Unless I can be sure I get a batch of 9V or 12V wall-wart that are identical and remove the 9V reg...?
Do I have any other choices? My only concern is cost. (Without affecting my circuit's proper operation)

hi Mike,
Sorry about the 'thank you' I was scrolling down the page with my mouse and I caught the button....:eek:
 
Mike,
If you have the odd components in your bits box, this is a very simple 5Vreg.
 

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Ok so I presume you meant 5V so I would do something like this?
power3.jpg

I believe the 5 Volts is more important than the 9 volts.
The 9V is for Op-Amp and a comparator which can withstand 2V to 16V

Oh and you are welcome Eric :)
And I should start using this thank you button as well, it is amazing how much help I have gotten by you guys on this forum.

Mike
 
Eric,

I am trying to save on cost of both components and PCB area and this is why I am trying to avoid having two regulators with its capacitors.

Mike
 
Eric,

I am trying to save on cost of both components and PCB area and this is why I am trying to avoid having two regulators with its capacitors.

Mike

Mike,
If you cut corners you will affect the performance of the circuit.
You should decide if you want a project that will do what you expect, but costs a little extra, or a project that you will never be satisfied with.
 
Yes I totally agree.

I do not want to compromise the operation of my circuit by saving on building cost but if I can save on building cost without compromising than I will take the extra time. This is my first project and the investment is coming straight out of my pocket so I am willing to spend a little time to save.

Mike
 
I have made my tests and I've concluded that I was going to reduce cost at the expense of heat so you were right Eric, I think I will keep my two regs and live with the extra cost.

Thanks you,

Mike
 
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