TREE

Who never used a multimeter Chinese yellowing that shoot the first resistor! Despite being heavily criticized, this multimeter is identical to any other, is a lightweight tool, compact, inexpensive and reliable. It has as main component IC 7106, which is an analog to digital converter, with output to liquid crystal display (LCD) 3 and 1/2 Digits.  The Marcelino (which may have other colors), has several brands and models, but his real name is 830, there are versions without the test transistors, there are also variants with signal generator 50Hz, thermometer, continuity test with back-light, etc. This multimeter can measure DC Volts 0.1 mV to 1000V, AC Volts 0.1V to 750V, Ampere DC 0.1 mA to 10A, Ohm 0.1 Ω to 2MΩ, diode and hFE for bipolar PNP transistors and NPN. Basic scheme of Digital Multimeter circuit diagram  

This circuit is a simple form of the commercial UPS, the circuit provides a constant regulated 5 Volt output and an unregulated 12 Volt supply. In the event of electrical supply line failure the battery takes over, with no spikes on the regulated supply. Circuit Diagram: Notes: This circuit can be adapted for other regulated and unregulated voltages by using different regulators and batteries. For a 15 Volt regulated supply use two 12 Volt batteries in series and a 7815 regulator. There is a lot of flexibility in this circuit. Circuit Diagram: TR1 has a primary matched to the local electrical supply which is 240 Volts in the UK. The secondary winding should be rated at least 12 Volts at 2 amp, but can be higher, for example 15 Volts. FS1 is a slow blow type and protects against short circuits on the output, or indeed a faulty cell in a rechargeable battery. LED 1 will light ONLY when the electricity supply is present, with a power failure the LED will go out and output voltage is maint...