Free Circuit Diagram

Metal Detector Circuit Topology One of the simplest method of metal detecting is by beat frequency oscillator. Basically, the circuit consist of two balanced oscillator. One oscillator provides the reference signal, and other oscillator is acting as the detector element. The reference oscillator’s frequency is fix, while the detector oscillator is variable depending on [...]

Notch filter is known as band-cut filter or band-reject filter. The fuction of this filter is to remove some frequency portion of a signal. The schematic diagram of this filter circuit, a second order notch filter is depicted in the figure below. The formula is actually complicated, but by taking the R3=R4 and [...]

Designing passive crossover network for your speaker system is easy, just like what shown in our previous crossover design article, but now we can design many types of crossover even easier using online crossover design tool. The crossover schematic diagram here is an example  with a case of 10 kHz high corner frequency, 1250 Hz  [...]

The excellent high input impedance, high slew rate, and high voltage qualities of CA3140 op-amp make it suitable for Wien-bridge sine wave oscillator. The basic circuit for Wien-bridge sine wave oscillator is shown in the figure below (the upper part). You can see the formula in the figure, when R1=R2=R, and C1=C2=C, then the formula [...]

A PLL system can be used to build a frequency-selective frequency multiplier by inserting a frequency divider inside the feedback path between the VCO output and the phase error detector input. Here is the schematic diagram of a low-frequency synthesizer with a programmable three decades divider circuit. The frequency-divider modulus N can vary [...]

The circuit below is a schematic diagram of a fast pulse detector. At 100 ns  or wider pulse width, the detection should be error free. At 60 ns pulse width,  the detection error should be under 10%. This circuit should be used to detect at least 100 ns wide pulse to ensure an [...]