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QUOTE="Alec_t, post: 1027487, member: 217914"]The LM358 can't source or sink much current (~10-40mA) so isn't really suitable for powering projects.[/QUOTE]

In that case just add a transistor. A few hundred mA possible.

 

Using a pukka voltage regulator gives you the advantage of overcurrent and overheat protection built in. If the 2N4401 output is short-circuited it would release its smoke and go the great electronics lab in the sky.

 

Using a pukka voltage regulator gives you the advantage of overcurrent and overheat protection built in. If the 2N4401 output is short-circuited it would release its smoke and go the great electronics lab in the sky.

VERY true. But just penny parts.

 

But just penny parts.

What price downtime?

 

Using a pukka voltage regulator gives you the advantage of overcurrent and overheat protection built in.

Can you show how that looks like?

 

There are ma

Can you show how that looks like?

There are many different voltage regulators available. Earlier in this thread I suggested the LM317.
If you look at the datasheet for this component, and scroll down to section 9, there is a typical application circuit, some design information.
http://www.ti.com/lit/ds/symlink/lm317.pdf

 

At Mouser, an LM317 costs $0.52 and an LM358 cost $0.37.

So, ignoring the other components you need, you would save 15 cents. While foregoing better regulation, better heat dissapation, short circuit protection, temperature protection.

I think you need to learn some design parameters beyond cost.

Bob

 

What price downtime?

Minutes. But I agree not a "quality design". Not a good design for a product but suitable for breadboard stuff.

 

There are many different voltage regulators available. Earlier in this thread I suggested the LM317.
If you look at the datasheet for this component, and scroll down to section 9, there is a typical application circuit, some design information.
http://www.ti.com/lit/ds/symlink/lm317.pdf

I meant specifically the pukka voltage regulator, never heard the term and couldn´t find anything related to electronics.

 

I meant specifically the pukka voltage regulator

Sorry. British slang made famous by chef Jamie Oliver.
From Wikipedia: "Pukka (Hindi पक्का, Urdu پكّاpakkā) is a word of Hindi and Urdu origin, literally meaning "cooked, ripe" and figuratively "fully formed", "solid", "permanent", "for real" or "sure". In UK slang, it can mean "genuine" or simply "very good""

 

What about something like this??

 

The pot wiring isn't quite correct and the 330 Ohm resistors for the LEDs would give about 32mA which is a bit much for standard LEDs. More normal might be 10mA for which 1k resistors would be needed. Amended diagram attached.

 

The pot wiring isn't quite correct and the 330 Ohm resistors for the LEDs would give about 32mA which is a bit much for standard LEDs. More normal might be 10mA for which 1k resistors would be needed. Amended diagram attached.

Thank you very much for that.

 

Ok, I'd like the current to flow through the resistor, through the LED and through the POT, could I do that by just inversing the order of the components in the line( from top to bottom: POT, LED, resistor)?
2 displays are meant to connect one in each to show voltage. The voltage supply is meant to be 9V, my main goal is to create two voltage rails with a LED, a switch and a POT (to select voltage) on each rail.

I would not use pots to adjust the led brightness I would replace the pot with a transistor and use PWM then you will have no moving parts!

 

Ok, I'd like the current to flow through the resistor, through the LED and through the POT, could I do that by just inversing the order of the components in the line( from top to bottom: POT, LED, resistor)?
2 displays are meant to connect one in each to show voltage. The voltage supply is meant to be 9V, my main goal is to create two voltage rails with a LED, a switch and a POT (to select voltage) on each rail.

The order doesn't matter.
It sounds like you are ready to get some hands on time with these things.

 

Sorry. British slang made famous by chef Jamie Oliver.
From Wikipedia: "Pukka (Hindi पक्का, Urdu پكّاpakkā) is a word of Hindi and Urdu origin, literally meaning "cooked, ripe" and figuratively "fully formed", "solid", "permanent", "for real" or "sure". In UK slang, it can mean "genuine" or simply "very good""

Origin brought over from the British Raj, and was popular British term throughout the latter 19th cent and into the 20th.
WAY before Jamie Oliver was born.
Max.