Delta Pulse

[Andi68]

And I see some nasty solder joints

[kt315]

why vd4 cathode on anode pad?

[chuubaba]

Thank you Jose. Anxiously waiting for your test results.
Don't know why the maker used such obsolete and widely counterfeit chips when other better and authentic options were there.
Safe journey.

[Jose]

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

In the distance, it is difficult to know what causes the malfunction of your DP.
The logical thing is to think that if it works with TL071, with LF356 or it should work better.
I am traveling now, in the next few days I will try my DP with TL071 to see what the difference is, and I will publish it.

[Andi68]

I should not write anything anymore, I do not know the DP

[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

[Andi68]

I think you have to match the circuit to the LF356

[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]

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

[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

[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 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]

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.

[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/measuring-internal-resistance-of-batteries/internal-resistance

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

[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