Just started MPP project

[multieagle]

I reinstalled the MOSFET and R1 resistor. TP1 remains the same. I have tried to get a larger sample rate. The directions state the Max real time sample rate is 48MS/s. Guess that means you have no control, the system displays real time, no exceptions???? It is a very simple, $89 computer based program. Hantek 6022BE version 1.0.4


Taking a rough measurement with cursor between pulses:

Cursor Time=922uB Frequency=108.5khz
Cursor Time=899uB Frequency=1.113khz

uB or u8 or ?

What do these figures indicate?

[multieagle]

Step 4, with coil attached, oscilliscope attached to damping resistor. Coil 354uH 1.3Ω Image attached.

[multieagle]

Step 5 Images

Testing Step 5. Images showing TP1 & TP3 Scope results

NOTE: Does not appear to recognize coil target. No change in voltage. I am getting 3.26v at TP3.

TP3 readouts (last image CH1)
Frequency 1.05KHz
Duty Cycle: 99 - 100%
Pulse: Between 944us - 4.7mS
Fall Time: 1.00uS
Rise Time: between 917uS - 2.8mS

[Chet]

Testing Step 5. Images showing TP1 & TP3 Scope results

NOTE: Does not appear to recognize coil target. No change in voltage. I am getting 3.26v at TP3.

TP3 readouts (last image CH1)
Frequency 1.05KHz
Duty Cycle: 99 - 100%
Pulse: Between 944us - 4.7mS
Fall Time: 1.00uS
Rise Time: between 917uS - 2.8mS

Hi multieagle


The scope display has low signal levels in millivolts. It should be swinging plus and minus 3-4v.


The voltage at TP3 should be around +0.9v to +1.0v. Measure for +4.75v on pin8 and -4.75v on pin 4 of U5. If they are off by more than 0.25v check the 5v power supply checks in step 1 and 2 of the build procedures.


Your scope has reached its limits on viewing fast pulses. The flyback pulse is 1 to 2 us in width. Your scope samples at 1 MHz which is a 1 us rate. You need at least a 10 MHz sample rate to resolve much fidelity on fast signals. You can still gleam some useful information but TP3 will be choppy and will lack some accuracy.


Does your scope probe have a voltage rating of 600v or higher? If not you could burn out the input circuit of your computer/oscilloscope by connecting to the damping resistor that has 450v present.


Regards,
Chet

[green]

Chet, maybe I just have no clue as to how an osilloscope works! Here is an interesting shot.

Some suggestions. Like Chet has said, make sure the probe is on x10 when looking at coil volts. I wasn't used to looking at high voltage circuits and learned the hard way. When posting screen shots have the scope attenuator setting match the probe setting (x1 x1 or x10 x10). Try using 1,2,5 and 10 usec/div. You should get a better display of flyback. Looking at the scope specs it looks like it should do whats needed. Vertical scale 50 volts full scale, x10 500 volts full scale.

[multieagle]

Hi multieagle


The scope display has low signal levels in millivolts. It should be swinging plus and minus 3-4v.


The voltage at TP3 should be around +0.9v to +1.0v. Measure for +4.75v on pin8 and -4.75v on pin 4 of U5. If they are off by more than 0.25v check the 5v power supply checks in step 1 and 2 of the build procedures.


Your scope has reached its limits on viewing fast pulses. The flyback pulse is 1 to 2 us in width. Your scope samples at 1 MHz which is a 1 us rate. You need at least a 10 MHz sample rate to resolve much fidelity on fast signals. You can still gleam some useful information but TP3 will be choppy and will lack some accuracy.


Does your scope probe have a voltage rating of 600v or higher? If not you could burn out the input circuit of your computer/oscilloscope by connecting to the damping resistor that has 450v present.




Regards,
Chet

I'm getting PIN4: +4.75V PIN8: +0.154
U4 still checks out okay.
TP2=+.031
Step 1: okay
Step 2: failed TP2



Hantek 6022BE has been discontinued, Specs:
Specifications:

Apprently it can sample up to 48MHz

Channels: 2
Bandwidth: 20MHz
Input Impandence: 1MΩ 25pF
Max. Sample rate:48MS/s
Vertical resolution: 8Bit
Gain range: 20mV-5V, 8Steps
DC accuracy: ±3%
Timebase range: 1ns-9000s, 39 Steps
Vertical adjustable: Yes
Input protection: Diode clamping
X-Y: Yes
Trigger Mode: Auto, Normal and Single
Trigger Slope: +/-
Trigger level adjustable: Yes
Trigger Type: Rising edge, falling edge
Trigger Source: CH1, CH2
Sampling selection: Yes
Waveform Display: port/line, waveform average, persistence, intensity
Network: Open/Close
Vertical mode: CH1, CH2, Dual, ADD
Cursor measurement: Yes
Math: FFT, addition, subtraction, multiplication, division.
Cursor: Frequency, Voltage
Dimensions: 205mm (L) x120mm (W) x35mm (H)
Accessories: Software CD, probes, manual, USB cord
Operating systems supported: Windows 7, Windows NT, Windows 2000,Windows XP, Vista

Features:

The unit conforms to the standard USBXITM interface, and can easily insert into a USBXITM housing allowing the user to build up a combination instrument.
USB2.0 interface, no external power source required, easy to use.
Suitable for notebook computers, or product line maintenance.
High performance, 48MS/s real-time sampling, 20MHz Bandwidth.
23 measurement functions, PASS/FAIL Check, be suitable for technical application> Waveform average, persistence, intensity,invert,addition, subtraction, multiplication, division,X-Y plot.
Saves waveform in the following: text file, jpg/bmp graphic file, MS excel/word file. FFT
One computer can connect many DSO, to easily extend channels.

[multieagle]

Question regarding NE5532
Can U5 NE5532 be replaced with NE5534? I've read that 5532 is dual, and 5534 singular, both used in audio applications. 5534 appears to produce less noise in professional audio systems. Reason for asking? I have several 5534's on hand, but nada 5532.

The 5532 is a dual high--performance low noise
operational amplifier. Compared to most of the standard
operational amplifiers, such as the 1458, it shows better
noise performance, improved output drive capability and
considerably higher small--signal and power bandwidths.
This makes the device especially suitable for application
in high quality and professional audio equipment,
instrumentation and control circuits, and telephone channel
amplifiers. The op amp is internally--compensated for gains
equal to one. If very low noise is of prime importance, it is
recommended that the 5532A version be used which has
guaranteed noise voltage specifications.


NE5534 Description
The 5534 is a single high--performance low noise
operational amplifier. Compared to other operational
amplifiers, such as TL083, they show better noise
performance, improved output drive capability and
considerably higher small--signal and power bandwidths.
This makes the devices especially suitable for application
in high quality and professional audio equipment,
instrumentation and control circuits, and telephone channel
amplifiers.
The op amps are internally--compensated for gain equal
to, or higher than, three. The frequency response can be
optimized with an external compensation capacitor for
various applications (unity gain amplifier, capacitive load,
slew rate, low overshoot, etc.) If very low noise is of prime
importance, it is recommended that the 5534A version be
used which has guaranteed noise specifications

[Chet]

Hi multieagle

Attached is a pcb layout with output voltages listed for the U2 oscillator that is used for the +5v power supply. If you don't have the voltages listed for D1, D2 and pin 2/C3 of U2 then U2 is probably bad. If you do have the voltages then U3 is probably bad. These voltages are referenced to TP10.

In reference to the information that green found and that you posted for your scope; post a display of TP3 with a faster setting of the horizontal sweep speed to somewhere around 20us or 50us and we can determine how well it will work for viewing the receiver functions.

Regards,
Chet

[Chet]

Hi multieagle

The NE5534 cannot substitute directly in place of an NE5532. It would require a new pcb with an extra socket to accommodate two NE5534s to replace one NE5532.

Regards,
Chet

[multieagle]

Hi multieagle


In reference to the information that green found and that you posted for your scope; post a display of TP3 with a faster setting of the horizontal sweep speed to somewhere around 20us or 50us and we can determine how well it will work for viewing the receiver functions.

Regards,
Chet

Re: TP3
I can get a trace at 50us, but it is too small for detail. I tried adjusting windows display resolution (Windows XP old laptop destined for recycling) but did not help. So, other than readout, trace is not much help at higher voltages. If I try to get a larger trace, say 20.0mV (highest setting) the vertical trace disappears off screen. Anything lower, and vertical trace porgressively falls to a straight line. I may be getting interference from the computer.

[multieagle]

Hi multieagle

Attached is a pcb layout with output voltages listed for the U2 oscillator that is used for the +5v power supply. If you don't have the voltages listed for D1, D2 and pin 2/C3 of U2 then U2 is probably bad. If you do have the voltages then U3 is probably bad. These voltages are referenced to TP10.

Regards,
Chet

U2 is BAD!

Thanks Chet & Green. Wish I could justify a better osilloscope.

[multieagle]

I can pick this up locally for C$150 http://www.amazon.com/Elenco-Oscillo.../dp/B0002EWO3K Is it a decent buy?

[green]

U2 is BAD!

Thanks Chet & Green. Wish I could justify a better osilloscope.

Hi multieagle. Still wondering why your scope won't work. I've tried to fix something more than once that didn't need fixing because the scope was on average and not triggered right. It looks like your scope uses averaging. I would like you to try. Channel 1 probe to TP1, 5 volts/div, display x1, probe x1. Channel 2 probe to coil(R3 or R1), 5 volts/div, display x10, probe x10. Trigger on channel 1(going negative). Time base, 1usec/div. Adjust trigger if needed for a stable display on channel 1.

[multieagle]

Thanks Green. That makes a difference. I might note that I can get nowhere near 1us/DIV.

[multieagle]

Thanks Green. That makes a difference. I might note that I can get nowhere near 1us/DIV.

I shot a short video using your suggested settings. I reversed probes, as I seem only to get a printout for CH1.

Link: http://www.undergrounddetectors.ca/DSC_2781.MOV It may take a while to load.

Data
Peak: 6.05V
Period: 946us
Freq: 1.06KHz
Time Rise: <1.00us
Fall Time: =894us