Arduino Nano VLF Metal Detector Project - Main Discussion

[kosacid]

i think its the OSC pulse being shared is causing the problems if you lift one of the OSC pins it works this is what i get on the OSC why do you need to sync the OSC anyway ?

[Qiaozhi]

If you don't sync the voltage converters, and allow them to run with the internal oscillator, then any switching noise will be asynchronous.
As you can see from my measurements, there is no problem with sharing the OSC pins.

[kosacid]

same frequency voltage when i test on the breadboard it works fine i put the same chip in the detector i even used the 5v on the Arduino with a 10k pullup attached to the OSC to make sure the clock is fine but still no negative voltage as you can see also i have bought chips of 5 different vendors i just cant work it out

i even tested that chip by exchanging the output capacitor for a resistor so you can see it syncs

[kosacid]

ok i have worked it out the OSC needs a stronger signal to work so pulling it up to 5v is not enough so i used pin 8 +12 and pulled pin 7 OSC up with a 5k resistor

[Qiaozhi]

Now I'm confused.
My build is working perfectly, and it's not the only one. I previously built at least two prototypes without any issues.
The OSC inputs are not being synced with 5V, as the collector of Q1 is pulled up to VREF which is 2.5V.
Have at look at Fig. 12 in the datasheet.
https://www.ti.com/lit/ds/symlink/lt1054.pdf

[kosacid]

Oscillator frequency VCC = 3.5 V to 15 V so 2.5 is not enough i tried with the 5v pullup that wasn't enough it needed just over 5v so i pulled up using the 12v it might be something to do with a 5v pwm 50/50 only gives you 2.5v just at the lower part of the trigger