Simple Timer circuit using CA3140 + NE555
This be the circuit sets the time to model is simple,at can fix the time had long ago and have tall good accuracy. By use pillar equipment be IC CA3140 for fix time mouth and NE555 perform sound electric bell origin. By we can fine time value done to a turn VR1 can fine since 10 second arrive at 3 hour. When the time expires will have an electric bell that a loudspeaker. For the equipment that should choose specially. Be C1 100uF 16V values should are a kind Tantalum. Because tall quality more Electrolytic. The moderately but if no …
6 ranges AC millivoltmeter circuits
Sometimes, we need to measure very tiny AC voltage and also high frequency. We cannot use a general meter. How it works This circuit can easily measure the very tiny AC voltage and high frequency 100 Hz to 500 Khz. Use an op-amp is the input is mosfet types, so has input impedance about 10 M ohms. The lowest full scale of this meter is 15 mV on a galvanometer 100uA. A galvanometer is a very sensitive meter to measure tiny currents, usually 1mA or less. It is analog multimeter, cheap and somewhat accurate. Best for observing the trend of …
The light meter circuit using a general diode
This is a simple light meter circuit using normal diode as a sensor and show amount of light by a any voltmeter. The light can change the properties of many devices, example.. LDR as photo resistors can change resistance by light. Photodiode- like LDR but sensitive better than LDR, because convert light into a electricity current. Some times general photodiode may be expensive and hard to buy. When the light to a silicon diode will have very tiny current So we can easily use it instead. The 1N914 is popular number, cheapest, small and clear body. In reverse bias form, …
Precision Peak voltage detector with a long memory time.
      If you want to check the peak voltage of the signal to change at any time. Measuring with a multimeter will not do it. We recommend this circuit. It may help you. We use this circuit The op-amp IC number CA3140 is the main equipment, acts as a voltage sensor that is accurate. So It is precision peak voltage detector circuit, and it remembers voltage value in a long memory time.       In this circuit is used with a positive signal input, when has negative feedback only. And the inverting input can only get some feedback, when diode D1-1N4148 is forward …