Voltage Regular and Nano

Other Hardware General Electronics
1

I can't understand why this is happening so hopefully someone here can help me understand this.

I'm trying to power a Nano off an LM317 with a steady 5 V. I'm using a breadboard with a DC power supply set to 14.3 V to test my circuit before I install it into my enclosure.

When I apply 5V and GND to the Nano, the DC power supply drops off from hitting the current limiter. If I apply more current, not only do all the LEDs light up but it fries it. I fried 1 and I thought it was the Nano so I tried a new one. Same issue...... This new one didn't fry since didn't touch the limit knob this time.

I tried an Uno on the same power supply circuit and it worked fine.

I moved over to a 7805 voltage regulator and used the Nano that didn't fry yet. It worked perfectly.

I tried troubleshooting my LM317 with a Nano installed but no applied power. I found that 5V and GND where shorting when a Nano was installed. When I unplug the Nano, the short goes away.

Faulty breadboard? I used the same breadboard with the 7805 to rule it out potentially.

Fake Nanos?

2

Hard to say.

Always show us a good schematic of your proposed circuit.
Show us a good image of your ‘actual’ wiring.
Give links to components.

3

What voltage setting resistors are you using with the LM317?

4

Sorry but no I did not make a schematic yet since this was just a prototype. These are parts I just have laying around so links for where these parts came from are impossible.

5

According to the equation for the LM317 Vout = 1.25( 950 / 240). I should roughly have 5 V. I've tested the output without a load on it and it produces the 5 V. Once the Nano is hooked up, it drops to about 2 V. For giggles I used a trimmer instead of a 950 ohm resistor and yeah that Nano made a visit to the grave yard.

Do think higher resistor values will help?

6

A correctly designed and constructed LM317 voltage regulator circuit, with fully functional parts, will work fine.

7

That looks fine. As jremington said after me :slight_smile:

Just check your nano is expected to be supplied with 5V , not 3V3. Other wise there is a fault somewhere on the Nano.

8

Capacitors?

Honestly, why use a linear regulator? They just convert excess voltage to heat, in this case:

14.3 - 5 = 9.3V
9.3 / 14.3 gives you at least 65% of your available power wasted as heat.

If this is coming from a battery (as I suspect given the voltages quoted) then that means at least 65% of the battery is doing nothing other than create heat. Complete waste. Use a buck converter.