Delta Pulse

[dbanner]

Overall, I think your problem is tinkering with the circuit to get the best performance for a given setup.
YOU MUST UNDERSTAND THAT DELTA PULSE IS NOT FOR VACUOUS ELECTRONICS YOUNG PLAYERS.

To your credit, you completed the project successfully. A miracle by any standard.

You should seriously consider a career in electronics engineering. You would need to take formal tuition of course, perhaps even register at a technical institute in your area.

Chuub, you show a penchant for blowing things up, smoking things out regularly, and avoiding catastrophic life ending electrocution.
I'd say you could at least make a First degree in electronics!!!!

Doesn't any neighbour ask themselves what is this guy doing with gloves and holding a long PVC pipe while walking around over some square contraption, with hands aloft holding coca-cola can? I'd be tempted to call the wagon from the funny farm to collect you.

[Jose]

I got the "potentiometers" from aliexpress but no info on data. There have been moments when i did suspect some smoke but the pots always read correct values on DMM. I test them as shown in youtube videos.
BTW there are few issues. Firstly it does not detect fast moving target near the limits of detection depth. Also it keeps ringing for some moments after a target has passed the coil. And finally the GEB and SENS pot make it most noisy instead of helping eliminate noise. With TL071 and LF357 the DISC pot does the same so i have to keep these three to minimum position. And finally i am amazed why MOSFET and VD1 don't get hot.

Some tips you can try to improve the performance of your DP.
First, it does not detect the target that moves quickly near the depth limits.
This is normal because the DP was designed to detect large and deep objects.
It also continues to sound for a few moments after a target has passed the coil.
Play with different coils and damping resistance, to improve this effect, even the working frequency.
The GEB and SENS pot make it louder instead of helping to eliminate noise. I am surprised why MOSFET and VD1 do not get hot.
It is possible that you are working with low frequencies and short TX pulse width, so it is normal that these elements do not get hot.
Try to increase the frequency, being careful with the pulse width so as not to heat the mosfet. at a multiple value of the network frequency. This will improve noise and responses to objects.

[chuubaba]

Vadim18 Dear with OP42 the detector is making so much noise despite all pots are on minimum level. Only way i can detect at this minimum level is by a little turn of the DISC pot. If i increase the DEPTH or T/HOLD then it again makes too much pulsating tone. Also low battery starts to blink and sound changes. I think OP42 will work best with this board but how to stop it from making so much noise? The LF355 did not work at all.

[chuubaba]

Dbanner I tried damping resistors 1k 820R, 735R, 713R, 697R, 682R, 680R, 330R etc in 1/4, 1/2, 3/4 and 1 watts. Its working most silent on 682R 1/2 watts and 697R 3/4watt damping resistor but still not able to keep it silent and stable in end part of T/HOLD pot. The SENS pot keeps making it noisy and unstable while discrimination is working excellent. Unfortunately not much improvement in detection depth. Air testing detects 400ml paint aerosol at around 70-75cm max. I am going to try new LF355 as i believe the one i got earlier died in transit and then move to ground testing. Please suggest how the ghost beeping in the last quarter of T/HOLD can be eliminated. I think whatever depth it has left is in the last bit of noisy unstable T/HOLD pot. My OP42 and TL71 chips are from very reliable source.
Jose thank you for valuable tips. Help me clear the last bit of T/HOLD pot. I am also considering to swap
all mylar caps with polyester.

[Jose]

Dbanner I tried damping resistors 1k 820R, 735R, 713R, 697R, 682R, 680R, 330R etc in 1/4, 1/2, 3/4 and 1 watts. Its working most silent on 682R 1/2 watts and 697R 3/4watt damping resistor but still not able to keep it silent and stable in end part of T/HOLD pot. The SENS pot keeps making it noisy and unstable while discrimination is working excellent. Unfortunately not much improvement in detection depth. Air testing detects 400ml paint aerosol at around 70-75cm max. I am going to try new LF355 as i believe the one i got earlier died in transit and then move to ground testing. Please suggest how the ghost beeping in the last quarter of T/HOLD can be eliminated. I think whatever depth it has left is in the last bit of noisy unstable T/HOLD pot. My OP42 and TL71 chips are from very reliable source.
Jose thank you for valuable tips. Help me clear the last bit of T/HOLD pot. I am also considering to swap
all mylar caps with polyester.

70, 75 cm for the object you mention is not bad.
I can tell you, what I found.
I use LF357 in the front and TL062 or TL072 in the other integrated ones.
When sensitivity is increased and the threshold is maximized, it tends to be noisy, but must be tolerable.
If the delay is set too low, it can contribute to instability, which is why the damping resistance must be carefully adjusted, in my case, it is about 470 ohms, or less. The coil that I currently use is 400 uH, and its resistance is from 2, to 4 ohms, depending on the size of the coil.
As I said before, the frequency of work if it is incorrect, will increase the noise and instability, if you are testing the DP, in the workshop.

[chuubaba]

...........70, 75 cm for the object you mention is not bad...............

This is sifted from repeated testing near end part of T/HOLD when the pot has five more minutes to go if it were arms of a clock. Otherwise 65cm is the rule on these paint aerosol.

When i use lower values of damping resistor such as yours the low battery indicator is ON and the detector sounds like an elephant.
Under no circumstances SENS pot helps rather the beeping goes wild even with a fraction of its turning (maybe a burned out pot ? or some i.c is dead?)
Thank you

[kt315]

145 page and again nothing new. лошадь ходит по кругу.
i reminder that DP is deeper and damping resistor in original board is 2k2. thats enough for 40us FIRST SAMPLE DELAY.
connect your fantazy to something another.
if you use poor battery thats answer. DP needs in good battery, with low minimalistic internal resistance.
ah ah ah.. we are not being aware that every battery has own internal resistance... luck of electronics basics?
https://learn.sparkfun.com/tutorials...nal-resistance

POOR BATTERY -> POOR RESULT -> MUCH OF INSTABILITY -> WHO IS QUILTY? -> kt315
and so always.

[Jose]

This is sifted from repeated testing near end part of T/HOLD when the pot has five more minutes to go if it were arms of a clock. Otherwise 65cm is the rule on these paint aerosol.

When i use lower values of damping resistor such as yours the low battery indicator is ON and the detector sounds like an elephant.
Under no circumstances SENS pot helps rather the beeping goes wild even with a fraction of its turning (maybe a burned out pot ? or some i.c is dead?)
Thank you

Play with different damping resistance values, even lower low values, should not turn on the LED, low battery.
Something is wrong.
What KT315 mentions may be happening.
On the value of the damping resistance, I comment here what gave me the best results.
I have no doubt that in the past different resistance values have been used, as well as coils of different inductances with different cables, etc. and different delays.

[chuubaba]

Jose with TL071 as DA2 i choose 100R 1/4W to give me best depth with full turning of T/HOLD and DEPTH pots without low battery indicator blinking. I tried with upto 15 volts from my DC power supply but no relief except with 100R. 400ml pwint aerosol at 75cm. 1footx1foot PCB at 103cm.
The voltage on -E is 11.76 volts when measured with DMM from terminal block. Is this good?
The 100R damper does not work at all with OP42.

[Jose]

Never try TL071 on the front, or OP42; I wouldn't know if it works well. I use LF357 and LF356 with good results.
The delay, power, threshold and gain potentiometers work well when the damping resistance is correct.
On the contrary, if the damping R is greater than necessary, these controls malfunction. Install the highest value, which allows the correct operation of the mentioned controls.
The DP will stop working and may be damaged, with voltages close to 15 volts. With 12 or 13 V, it is enough to get a good sensitivity.
The voltage -E, is equal to the supply voltage, less the drop in the union of the diodes of 0.6 to 0.7 volts each, (1.2 to 1.4 volts).
For your information, I use 200 Hz with large coils and 400 to 450 with medium coils. I didn't get good results at 100 Hz, I don't say it doesn't work.

[chuubaba]

Jose I used new LF356 today with different frequency and damping resistors but it is almost impossible to get this detector to settle down with this chip. With some damping resistors the detector would be dead silent and all pots seem to work (because turning them doesn't cause it to go crazy noisy) but It would detect only when a target is directly touching the coil and otherwise it is so much noisy that it is impossible to tell a detection.
Any suggestions in the circumstances? I am going to change all pots anew tomorrow.
Thank you

[Andi68]

If the chip was bought in China, then it could be a fake

[chuubaba]

Andi68 With some damping resistor + LF356 the detector is absolutely obedient no noise no chatter and i can turn all pots to maximum without much noise but it detects no target whatsoever. Whats else can cause this non detection other than LF356? $he same board works with TL071 but depth not as expected.
Thank you

[Andi68]

I think you have to match the circuit to the LF356

[chuubaba]

I think you have to match the circuit to the LF356

Which components precisely? I got no idea what to change. All components according to latest BOM for DP REV5.
Thank you