CLF-Meter

Contents

CLF-Meter

$/!\$ Vorläufig / Preliminary, work in progress $/!\$

At https://www.banggood.com I have seen a low cost (12 EUR incl. shipping) DIY Inductance Capacitance Frequency Meter Tester Kit (ID: 1360199) with a processor STC89C52 and a housing (Acryl).

Unfortunately no documentation was offered.

It was delivered within 14 days, and now the search for the documentation started.

A kit with the name secohmmeter-capacitance-meter-inductance-meter-frequency-meter was offered from company saintsmart.com, and they had a link to the documentation (schematic, C source code).

All electronic parts are clearly labeled on the upper side of the PCB. But with a schematic it is a lot easier to understand.

A Video about the kit is also helpful, especially the comments.

A mouse click on a picture will increase to to a bigger size.

I will try following to improve the documentation.

Resume

Unfortunately the Inductor measurement does not work.
The accuracy is not specified.
I did not found any explanation about the measuring principle.
It is better to buy the LC-Meter.

Parameters

Supply voltage: DC 5 V or DC 8-14 V or AC 7 to 10 V
Board size: 6.8 * 8.5 cm
Small capacitance measurement range: 1 pF - 2.2 μF (no polarity capacitor)
Inductance measurement range: 0.1 μH - 1 H
Frequency measurement range: 20 Hz - 400 KHz (measured small signal)
Electrolytic capacitance measurement range: 0.5 μF--12000 μF (small / big switch)
LCD display: 16 characters per line, 2 lines
Accessories: Clip for 9 V battery
Accuracy: Not specified

Usage

See the picture above.

There a 4 x 2-pin screw terminals for the DUT (Device Under Test):

# from left to right
Capacitors|Inductors|Frequency| polarized Capacitors
                     IN    GND  IN    GND

There are 6 push button toggle switches:

# from left to right
                                           Power ON
Capacitors|Inductors|Frequency |big pol. C|small pol. C

$/!\$ Before you measure release all measuring switches. Only one switch at a time must be on.

Current consumption: about 43 mA (inklusive LCD background illuminiation)

Electronic Details

CPU: STC 89C52RC, 80C51 Derivat
- Clock: 12.0 MHz
LM393, Dual differencial Comparator
Reference inductor: L1 100 uH, 0.6 Ohm
Reference capacitor: C12 1.0 nF, C13 1.0 nF (replaced by 1% type)
Power supply input could be either AC/DC because of D1 - D4
R16 should be adjusted to 0.6321 x Vcc
- e.g. 5.096 V * 0.6321 = 3.221 V, measured at pin 5 of LM393

Housing

The housing is made well, with some exceptions:

The mounting of the PCB is done with 2 screws from the bottom side, see the picture on the right.
On the left side a cutout for the 10 pin programming plug for the CPU is missing. See the picture below on the left.
On the right side a 10 mm diameter hole is missing for the power supply plug. See the picture below on the right.
I left the front side off for 2 reasons:
- Allow to easy access the battery.
- Allow short pins for the test objects.

Accuracy

Capacitors: not measured yet.
Inductors: Measuring does not work!

Temperature Drift

If the zero point drifts, it will be shown if the C- or L-button if OFF and the mode was selected before.

Contact Email, please enter your Email address

$/!\$ The entered Email address will not be published, or given away.

Comment this page
Name:
Comment:
Are you human?

List of pages in this category:

-- RudolfReuter 2018-11-13 18:03:21

Go back to CategoryTechDoc or FrontPage ; KontaktEmail (ContactEmail)