felezjoo PI(the best pulse induction metal detector that I made until now)

[waltr]

if I use two 9v batteries it works fine but they discharge in 30 minutes. if I use 3x6v 4ah in series (19.5V) lead batteries the 7812 becomes hot instantly and goes into protection. I do not understand why...

Guess the 9V batteries are to small 'transistor' battery- These are for low current draw and will Voltage drop on higher current.
Whereas, 4A-Hr lead acid batteries will hold their Voltage with quite a current draw.
Therefore, The 9V batteries Drop Voltage = less Voltage drop on 7812 = less heat. but very short operation time.
Then the lead acid batteries do not Voltage droop = higher V drop on 7812 + more current to circuit (TX) = more heat.

[useus]

to measure the circuit I would have to repack, I'll do it tomorrow. out of 7812 should be 100ma right?

[useus]

950ma measured by the battery... what can it be?

[useus]

no, only 7812 are very hot (with heatsink)

now i try to measure ampere

[dbanner]

Does the circuit work, anything else getting hot on PCB?

[dbanner]

The l7812cv is [email protected], this should be adequate for circuit. Assuming you have it on heat sink, then circuit has problems.

[dbanner]

Put meter in series with circuit and measure current draw. Then put meter before regulator and measure current draw. It could be the regulator itself.

[useus]

apparently I have no shorts on the circuit.

probably if there was a short it would not work even with the two 9v batteries

[useus]

L7812CV... to220

[dbanner]

If I remember correctly, the L7812(TO92) is only rated for 100mA. It will definitely go into thermal shutdown.

[dbanner]

That's not good. Which 7812 are you using? I assume it is 7812ct(to220 package)?
Or is it the to92 package?
If it's the 7812ct, then something is sinking too much current in the circuit.

[useus]

if I use two 9v batteries it works fine but they discharge in 30 minutes. if I use 3x6v 4ah in series (19.5V) lead batteries the 7812 becomes hot instantly and goes into protection. I do not understand why...

[basellafe]

https://www.epal.pk/product/atmel-atmega328p-pu-microcontroller-dip28-package/

[chuubaba]

So there are different types. What type i should buy now? How i recognize its the right type? And BTW which arduino you are using for this I am using arduino uno.

i think your problem is the tybe of atmega about this connection i write fuses a handreds time

[basellafe]

i think your problem is the tybe of atmega about this connection i write fuses a handreds time