Description:
The circuit consists of comparator U1B, discharge transistor Q1, Q2, etc. Set the forward input of the comparator to Uc, (Uc = 0.632E,
The Rref is adjusted, and the measured capacitor CEx is connected to the reverse input terminal. When the pin of P15 is low level, the capacitor discharges.
Note that the pull current of 51 single chip pin is very small, and Q1 can not be directly driven, otherwise the discharge time will be very long.
When P15 pin of MCU is high level, capacitor charges, when charged to Uc, comparator flips and triggers outside MCU.
The capacitance can be calculated by measuring the charging time and the charging resistance.
Parameter:
Board size: 8*6CM;
Supply voltage: DC 9-12V (the power supply range is still relatively wide)
Measuring range:
Inductance measurement range: 0.1μH--------1H
Small capacitance measurement range: 1pF-------2.2μF (no polarity capacitor)
Frequency measurement range: 20Hz ------400KHz (measured small signal)
Electrolytic capacitance measurement range: 0.5μF--12000μF (electrolytic capacitor)
F theoretical frequency measurement 0-500k, sampling error within a few hz, but there are certain requirements for the input signal, because Schmidt trigger is not used, so it is only used to measure the ideal waveform with less common mode interference.
Note the following points:
1. Because it is a DIY product, there is no rounding and false optimization of readings. The actual test value is real-time data, and the mantissa will continue to jump normally;
2. Test contact as far as possible to be reliable and good;
3. After testing the components to be tested, release the test and avoid hand interference to affect the reading.
4. The power supply is critical. A bad power supply can increase the test error and data jitter, which can seriously damage the 393 chip. It is therefore recommended to use our recommended power supply.
5.Because there is no standard measuring tool at hand, it is impossible to measure the test accuracy of this product. This product is used for general programming, learning, and production. If you require high precision, please do not purchase it. Thank you.
| Name |
Parameter |
PCB Mark |
Quantity |
| Resistor |
1K |
R4 R8 R9 R11 R12 |
5 |
| 10K |
R2 R17 R18 |
3 |
| 100K |
R5-R7 |
3 |
| 2K |
R1 R13 |
2 |
| 100ohm |
R14 |
1 |
| 47K |
R3 |
1 |
| 5.6K |
R15 |
1 |
| Adjustable potentiometer |
502(5k) |
RP1 |
1 |
| IC |
89C51 |
U1 |
1 |
| lm393 |
U2 |
1 |
| Inductor |
100uh |
L1 |
1 |
| DIP 16 hole |
|
|
1 |
| Self-locking switch |
|
|
5 |
| Electrolytic capacitor |
470UF |
C4 |
1 |
| 10UF |
C7 |
1 |
| 1UF |
C5 |
1 |
| Monolithic capacitor |
105 |
C14 |
1 |
| Crystal |
12MHz |
Y1 |
1 |
| Diode |
IN4007 |
D1 |
1 |
| Resistor packs |
10K |
J1 |
1 |
| Adjustable resistor |
10K |
RP |
1 |
| LED |
3MM red |
D5 |
1 |
| IC socket |
40P |
U1 |
1 |
| 8P |
U2 |
1 |
| Ceramic capacitor |
102 |
C12 C13 |
2 |
| 22P |
C1 C2 |
2 |
| Regulator |
7805 |
V1 |
1 |
| LCD screen |
LCD1602 |
|
1 |
| Transistor |
9015 |
Q1 |
1 |
| 9014 |
Q2 |
1 |
| Self-locking switch cap |
|
|
6 |
| Power socket |
DC5.5V |
|
1 |
| Female pin header |
16p |
JP1 |
1 |
| Pin |
4P |
|
1 |
Package Included:
1 x DIY High Precision Digital Inductance Meter Kit
