A high-quality microphone preamplifier using a single power supply, suitable for dynamic or electret microphones. All right reserved to Andy Collison, the author of this preamplifier, more info [here](http://www.zen22142.zen.co.uk/Circuits/Audio/lf071_mic.htm)
# Addition for STM32 discovery/nucleo for L/C measure #
![LM 393 LC meter.jpg](//image.easyeda.com/pullimage/Xf9og3xv0VKbZ6QSkXsz1Y2ViCPYv6ay1rW9pzmY.jpeg)
![disco sh plus lcm merged top.jpg](//image.easyeda.com/pullimage/PH0RNomSP4RWTe5KR26NjTiPTzkTe94ACJlbghgD.jpeg)
![disco sh plus lcm merged bottom.jpg](//image.easyeda.com/pullimage/thOhv5tdVPsLGIBEYk4NwwL7T9XWhP1WPlvRs2zS.jpeg)
![556 C meter 2 ranges.png](//image.easyeda.com/pullimage/sRbpQWtQFjjlgqhuY0fywZnC8BT5Q9rVEZ06BTHK.png)
Using 555/6 as a multivibrator we can measure the capacity of the connected capacitor.
At all times, the 555/6 charges to 2/3 VCC and discharges to 1/3 VCC the connected capacitor, supplying a rectangular signal at the output in accordance with the capacitor charging and dischar...
1. For L/C meassure by LM311 and oscillation circuit.
2. For FREQ meassure by special input circuit with a capacitive coupling
3. For C meassure by 556N freq to C - range 1-1000 pF
4. For C meassure by 556N freq to C - range 1-1000 nF
![multi freq meter V_02 cover.jpg](//image.easyeda.com/pullimage/YyWhE1CwRVAFl7XpCxxjQZ6YGdweU7GAEVO5MXL3.jpeg)
![multi freq meter V_02.jpg](//image.easyeda.com/...
# Legendary LM311 comparator - addition for STM32 discovery/nucleo for L/C measure #
![LM 311 LC meter.jpg](//image.easyeda.com/pullimage/7Okxq5DykgHnCnwNFLRkTub2UYa9Lmh6a4129xz4.jpeg)
![disco sh plus lcm merged top.jpg](//image.easyeda.com/pullimage/LQC1eyRJZIRFOzxIL3IuzkEtYxhQRH4rhLdPK3nV.jpeg)
![disco sh plus lcm merged bottom.jpg](//image.easyeda.com/pullimage/QNkrlEUThEK3aEwsCeKzoxJosEpS...
![555 C METER.png](//image.easyeda.com/pullimage/mcOJA7x4P3U8o93umkhTMK6P1FIKYIFxnxxfelKd.png)
Using 555 as a multivibrator we can measure the capacity of the connected capacitor.
At all times, the 555 charges to 2/3 VCC and discharges to 1/3 VCC the connected capacitor, supplying a rectangular signal at the output in accordance with the capacitor charging and discharging cycle....
The Arduino platform has become quite popular with people just starting out with electronics. It is an open-source hardware design, based on microcontroller board designs and provide sets of digital and analog I/O pins that can be interfaced to various expansion boards ("shields") and other circuits. The boards feature serial communications interfaces, including USB on some models, for loading pro...
This is a custom - Arduino uno - based circuit.
- Microcontroller: Atmel ATMega328p
- Bluetooth Module: Support HC-06 & HC-05
- Motor Driver IC: Two L293D (up to 4 DC motors or up to 2 stepper motors)
- Servo motor header
- 3 input/output pins (Can be used to connect LEDs or button SWs)
- Programmable header
- Reset button
DIY Hot Air Station using Arduino (ON/OFF Based Heat Controller).
Arduino Pro Mini for all the magic.
TM1637 4-Digit Display Module for display purposes.
LM358 based amplifier to read thermocouple voltages for measuring current temperature.
4 buttons to set the desired temperature required.
BTA16 with MOC3041 and other suitable passives as the heater controller.
Manual temperature calibration is n...
# UM66T Melody Generator
An UM66T generates various Melody Tunes when triggered which can be used in car/scooter reverse signals, doorbells and toys.
**Order PCB:** [PCBWay](https://www.pcbway.com/project/shareproject/Musical_Bell.html)
## Electronic Components
| Qty | Comp...