Archive for category: Measurement Circuits

Thermal Fan Controller by IC 741 and Diode

Measurement Circuits | By: Diagram mania

The controller uses one or more ordinary silicon diodes as a sensor, and uses a cheap opamp as the amplifier. I designed this circuit to use 12V computer fans, as these are now very easy to get cheaply. These fans typically draw about 200mA when running, so a small power transistor will be fine as […]

Water level Indicator by LM393

Measurement Circuits | By: Diagram mania

Simple, two-wire, remote monitoring unit Three-LED level display, 9V battery powered The whole project was developed on a friend’s request. Its purpose was to remotely monitor the water-level in a metal tank located in the attic by means of a very simple control unit placed in the kitchen, some floors below. Read more original source: […]

Water Drain Pump Controller by IC 4013

Measurement Circuits | By: Diagram mania

A hole needs to be digged at the lowest place in the celler that have water incomming problems. The hole is about 0.5 x 0.5 x 0.5 meter, at the bottom a large water pump is mounted. Then the different water levels was measured, so we know how to make the sensors. Read more original […]

Stud Sensor Automatic

Measurement Circuits | By: Diagram mania

This is an old discrete component design, now superceded by a PIC. This thing is a very nifty capacitive sensor. For you europeans, this little gem is used in north america mostly for detecting wooden beams behind drywall or plaster. I’ll take one of these over the new design any day, because these ones don’t […]

Lightning Storm Detector

Measurement Circuits | By: Diagram mania

Detects approaching lightning storms by monitoring the RF spectrum Reverse engineered schematic diagram of a mass produced lightning detector. The RF signal from lightning is quite strong and broad in spectrum so a tuned circuit is not required at the antenna input stage. Too much sensitivity will cause false alarms in a simple receiver such […]

Metal detector by IC 4093

Measurement Circuits | By: Diagram mania

The circuit shown must represent the limits of simplicity for a metal detector. It uses a single 4093 quad Schmitt NAND IC and a search coil — and of course a switch and batteries. A lead from IC1d pin 11 needs to be attached to a MW radio aerial, or should be wrapped around the […]

LED VU Meter by IC LM3914

Measurement Circuits | By: Diagram mania

This is Circuit LM3914 LED VU Meter. use IC LM3914 and Transistor BC109C. For Display power Music by LED This be LED VU Meter by IC LM3914 circuit show with LED convenient for the stereo or sound all signal. This easy circuit again because use IC LM3914 show get 10 the level. Build easy because […]

Bridge Amplifier by LM741

Measurement Circuits | By: Diagram mania

Circuit Bridge Amplifier by LM741

Electromagnetic Field Detector with IC UA741 or LF351

Measurement Circuits | By: Diagram mania

This circuit is sensitive to low frequency electromagnetic radiation and will detect for example hidden wiring or the field that encompasses a transformer. Pickup is by a radial type inductor, used as a probe which responds well to low frequency changing magnetic and electric fields. Ordinary headphones are used to for detection. The field that […]

FREQUENCY COUNTER USING PIC16F84

Measurement Circuits | By: Diagram mania

This is a simple frequency counter based on a micro-controller PIC16F84. Its maximum working frequency is around 30MHz, and have a 10Hz resolution, and having low current consumption (15mA), and very simple assembly. This uses 7 numbers seven segment LED display to display the frequency. The electrical schematic is very simple, given that most of […]