Frequency measurement with red frequency meter module

[electronium]

Hello guys, I hope you are doing well
Is it possible to measure city electricity frequency and pwm peak of power transistor with this module? How is it possible?

 

[Tony Stewart]

Also if using a switch to Gnd from a storage cap, use very small C to limit charge energy as the ESD diodes are very tiny to make them faster than the CMOS SCR pnpn substrate.

 

[Tony Stewart]

I was incorrectly assuming the ESD protection design for I/O ports is the same as Input only. It now seems to be a well guarded secret how they make ESD protection. Some vendors are considering pnpn SCR clamps to Vss & Vdd as a low C solution for high speed logic, which will handle driver currents but make the device not function until power is recycled.

Also not all outsourced IC fabricators use the same ESD design, so it is important to verify all your assumptions. Also the design changes as lithography shrinks and devices get fast so the diodes must be faster and smaller too to limit pF of the diodes which affects input risetime.

We also assumed you know the max voltage rating for resistors.

If the resistor is connected to the grid, you better not rely on one 250V rated R when 3kV transients ought to be expected.

Yety Microchip assume you understand this. But they do understand the current limit is protected by the internal dual stage ESD protection. High means 110 rms 60Hz and 162Vpk

i.e. DO NOT DO THIS with one 1/4W resistor rated for 250V


http://ww1.microchip.com/downloads/en/AppNotes/00521c.pdf

p1

Don't confuse system level ESD tests with high current compared to human body model (HBM) 100pF tests for IC protection.

Microchip says ...

Although most silicon is warranted to survive some level of contact with ESD HBM peak currents, they generally are not warranted to survive 5.5x higher IEC 61000-4-2 peak surge currents without external ESD protection logic. The ratings that are used for protecting ICs in the manufacturing environment, such as HBM and CDM, are not equivalent to system level ESD tests in IEC 61000-4-2)

What happens with latchup?

Well with 18V CD4xxx series the chip gets hot but due to high resistance usually survives, but with lower voltage devices like 5.5V 74HC and 3.6V 74ALC family the RdsOn is now reduced to 50 and < 25 ohms respectively, so the chip is more likely to silently "burn" out a weak link and you may smell epoxy but no outer visible signs.

 

[rjenkinsgb]

5.1V Zener and Vf reverse may be too much

Oops, not paying attention - I said to use SCHOTTKY diodes back in posts #8 & 10, I never noticed the symbol was wrong!

The 100K series resistor with low voltage inputs would keep things safe anyway, I'd just rather have better protection against accidental higher voltages & spikes.

 

[Tony Stewart]

Oops, not paying attention - I said to use SCHOTTKY diodes back in posts #8 & 10, I never noticed the symbol was wrong!

The 100K series resistor with low voltage inputs would keep things safe anyway, I'd just rather have better protection against accidental higher voltages & spikes.

They work fine.. I verified it

 

[electronium]

And this attenuator part, to fit at the 240V source being measured, reduces the voltage so it can connect to the above circuit:

View attachment 143753

If you are going to probe different AC sources, build the attenuator in to something like an old ball pen casing to use as a handheld probe and use screened cable to connect to the meter part.

Video of testing and checking the city's electricity frequency

 

[electronium]

Does anyone know what this button does?
muti mod state push botton

 

[electronium]

OK:

This part converts the PIC logic level input so it's safe for general use at low voltages, so should be permanently connected to the module; fit it in whatever casing you use for that:

View attachment 143752

I am implementing the circuit test and check on the board, are both zener diodes?
D2 goes to which IC pin? And can I put D2 fast?

 

[rjenkinsgb]

I am implementing the circuit test and check on the board, are both zener diodes?
D2 goes to which IC pin? And can I put D2 fast?

They should both be Schottky diodes, not zeners. eg. BAT48 or any schottky signal diode.
Schottky diodes conduct at around 0.4V, compared to normal diodes conducting at about 0.6V

The top of D2 connects to the 5V supply somewhere on the module - it goes to Pin 14 on the PIC according to the diagrams of the module that you posted earlier.

It's a very common circuit used to protect IC input pins from excess voltages. If the voltage is negative of ground or positive of the positive supply, one or the other extra diodes conducts and stops the voltage getting to the point the IC input circuit can be damaged.

 

[electronium]

They should both be Schottky diodes, not zeners. eg. BAT48 or any schottky signal diode.

I don't have the bat48 diode available, can I replace the 1n5819 diode?

 

[rjenkinsgb]

I don't have the bat48 diode available, can I replace the 1n5819 diode?

Yep, they look fine.

 

[electronium]

OK:

This part converts the PIC logic level input so it's safe for general use at low voltages, so should be permanently connected to the module; fit it in whatever casing you use for that:

View attachment 143752

I implemented this schematic and sent the result in the form of photos

The photo above shows the yellow test point wire from the collector of the 13001 transistor leading to the primary of the Chinese 5v 0.5A charger transformer.
The purpose of the experiment was to measure the high voltage pwm frequency


Circuit review link and relevant test video

 

[electronium]

verify below before doing above . 5.1V Zener and Vf reverse may be too much
View attachment 143775

View attachment 143776
View attachment 143777

5.1 V @ 47mA using this model with 12V rms you actually get 10% more typ. with no load on transformers so assume exact input V output is 13.2rms no-load.

Then with this Zener model due to 100k Vp,Ip are; +5.01 V and -10 mV at -155 uA pk sine so Good.
View attachment 143778

I like using simple Falstad's browser simulator OR any tool you know how to specify exactly.

http://tinyurl.com/2xcbkoaj

Once you have verified and understood diode VI response, you can do this approx in your head.

I did the test, I sent the video, you can see, for a moment, the display shows the number 0.001, then it goes back to zero, is that number pwm switching frequency?
10khz?
Or is it a filter number related to noise?
which is it

 

[electronium]

OK:

This part converts the PIC logic level input so it's safe for general use at low voltages, so should be permanently connected to the module; fit it in whatever casing you use for that:

View attachment 143752

12v ac of transformer frequencymeter
I proceeded according to your circuit, but the result was different, as if the module and source were shorted, I sent the video of its review below
test and analys this video

 

[rjenkinsgb]

Go back and read posts 12 - 14 again.

The 100K and diodes circuit is protection for low voltages only.

You need the extra part with the 1M and 47K divider wire before the low voltage part for high voltage inputs such as the SMPSU primary.

How have you isolated the AC supply to test the SMPSU?

Note also that breadboards and long open wires are not good at high frequencies.

 

[electronium]

I really went ahead with what you said, even my reports and results are not abstract, I sent them all with pictures and videos, I implemented the circuit on the board without a single error, but I could not achieve the work and what I wanted.
I bought this module so that when I don't have an oscilloscope, it will be my tool to measure switching frequency and pwm voltage and high frequency with this device.

 

[rjenkinsgb]

I really went ahead with what you said

So where is the 1M : 47K divider, prior to the 100K and diodes?

 

[electronium]

So where is the 1M : 47K divider, prior to the 100K and diodes?

Unfortunately, I don't understand without a circuit diagram
12 volts ac is not important, it is important to measure the high voltage that comes from the collector and drain and the base and gate of the transistor for each of the activities, I do not know what I should do to achieve the desired demand and the frequency can be shown by the module
It was a resistance division for city electricity voltage, are the same resistance values suitable for the city electricity peak which exists as pwm from the drain and collector of the transistor?
How much voltage can the input of this module withstand without a protection circuit and not burn?

 

[danadak]

A lot of folks seem to have issues with this module, see comments here :

Amazon.com

Manual attached.

Sound card oscilloscope, MAKE SURE YOU PROTECT SOUND CARD INPUTS before you
do this :

But first build a simple circuit to protect sound card inputs so you do not
ruin from transients, overvoltage. Google "protect sound card input".


For example http://makezine.com/projects/sound-card-oscilloscope/

Post #17, oscilloscope only good for ~ audio frequency range

question about speaker crossover

I am making a really simple cheap speaker (consisting of bluetooth amplifier ZK-502C, Dayton audio TCP115-4 and Dayton audio ND16FA-4) and i need a capcitor to cut low frequencies for tweeter. Usualy i used a electrolytic or ceramic capacitor to cap it at around 3500Hz. But today i read a guide...

www.electro-tech-online.com

Other DIY oscilloscope projects : https://www.youtube.com/results?search_query=arduino+oscilloscope

DIY Frequency Counter : https://www.pjrc.com/teensy/td_libs_FreqCount.html Uses your PC
com port as display.

Scope into Mhz range : https://www.sillanumsoft.org/


Regards, Dana.

 

[rjenkinsgb]

Unfortunately, I don't understand without a circuit diagram

Both halves of the circuit are in posts 12-14. The high voltage part feeds the low voltage part.

 

[electronium]

According to the fact that friends and colleagues took the trouble to do some answers with software analysis, we want this topic to end, why can't this module measure the switching frequency? It is correct to use the sound card as an example instead of the scope, but we want to proceed with this module... I will show you in a few more posts, even though I connect it directly from the base and gate transistor to the module, it does not show the frequency. We are here for the proverb that says that the engineer congregation will either build a way or find a way