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This circuit was designed to charge Nicad battery packs in the range of 4.8 to 15.6 V from a convenient remote power source , such as automobile battery. When power is first applied to the circuit applied to the circuit , a small bias current supplied by R1 via winding L1 , starts to turn on the transistor TR1. This forces a voltage across L2 and the positive feedback given by the coupling of L1 and L2 causes the transistor to turn hard on , applying the full supply across L2. The base drive voltage induced across L1 makes the junction the necessary base current to hold Q1 on. Component List Resistor R1 = 1M R2 = 120R R3 = 10R R4 = 39R Capacitor C1 = 100uF 25V C2 = 0.01uF C3 = 4700pF C4 = 100uF 25V Diode D1 = 1N4148 D2 = BYV27-5 D3 = BYV27-5 Transistor Q1 = ZTX650 Transformer L1 = 12T 36awg L2 = 13T 36awg L3 = 20T 30awg L4 = 40T 30awg Core FX3437 with gap of 0.08mm Former DT2492

This electronic circuit is a simple VHF FM transmitter circuit. The circuit can easily make portable use for a small 9 volt battery. Transmitter range from 60 to 100 meters range.  The construction of the circuit is very simple. Electrically adjustable frequency between 88 and 108MHz. Portable and low power consumption. You can use any FM receiver. 9 Volt works. Portable and Low Power VHF FM Transmitter Circuit Diagram Parts list: R1 = 10K R2 = 15K R3 = 3.3K R4 = 470 ohm R5 = 100K R6 = 4.7K VR 1 = 10K Pot meters VALUE C1 = 0.1uF----- 104 C2 = 0.001uF---- 102 C3 = 0.0015uF---- 152 C4 = 10pF ----- 10 C5 = 3pfF ----- 3 C6 = 2.5pF----- 2.5 C7 = 10pF ----- 10 C8 = 0.01uF---- 103 C9 = 0.022uF----- 223 C10 = 1pF ----- 1 C11 = 0.001uF---- 102

a AM portable ​​radio receiver using ZN414 IC. The ZN414 ic has now been replaced by the MK484 which is identical in performance and pinout. Designed around the popular ZN414 IC this receiver covers the range of medium wave band of approximately 550 to 1600 KHz with the values ​​indicated. The condenser coil and tuning can be taken from an old MW radio to save time. The ZN414 IC, has been replaced by the MK484. The integrated circuit is a 3 pin, tuned circuit radio frequency, and incorporates several RF stages, automatic gain control and an AM detector. It's easy to overload and voltage of th IC is critical to success. In this circuit a small voltage regulator turns on the transistor BC108B, 1N4148 diodes four, 2k7 and 10k resistor and the resistance of pre 820R. The 10k pot control acts as a receptor selectivity for all, control the operating voltage for the ZN414 (or MK484). The audio amplifier is built on an investment of 741 op-amp amplifier circuit. Additional current pulse i...

This portable AM and FM radio circuit is designed using the LA1800 IC and some other external components. As you can see in this circuit diagram the LA1800 manufactured by Sanyo Semiconductors , require few additional components. The LA1800 am FM portable radio circuit needs to be powered from a 3 volt DC power supply circuit. AM and FM Radio with LA1800 Portable Project You can use an 3 volt battery. This radio receiver circuit has a low current dissipation of 5.6mA for FM band and 3.2mA for AM band .Also the output signal is driven into earphone speakers , but you can use an additional speaker ( in that case you need to connect an additional small power audio amplifier).

This is a small, portable set, designed for those aiming at look improvement. The Bio-Stimulator provides muscles' stimulation and invigoration but, mainly, it could be an aid in removing cellulite. Tape the electrodes to the skin at both ends of the chosen muscle and rotate P1 knob slowly until a light itch sensation is perceived. Each session should last about 30 - 40 minutes. Circuit diagram : Portable Muscular Bio-Stimulator Circuit Diagram C1 generates 150µSec. pulses at about 80Hz frequency. Q1 acts as a buffer and Q2 inverts the polarity of the pulses and drives the Transformer. The amplitude of the output pulses is set by P1 and approximately displayed by the brightness of LED D1. D2 protects Q2 against high voltage peaks generated by T1 inductance during switching. Parts : P1-----4K7 Linear Potentiometer R1-----180K   1/4W Resistor R2-----1K8  1/4W Resistor (see Notes) R3-----2K2  1/4W Resistor R4-----100R   1/4W Resistor C1-----100nF  63V Po...

Here is a low-cost Electronic Circuit Project of Portable Battery Powered USB Charger Circuit . This circuit is able to charge your PDAs, Ipods, Mp3 players and any device that plug in to a computer USB to charge. If you fit this circuit in a small box with a 9V battery then it will become a portable emergency USB charger. Low-Cost Portable Battery Powered USB Charger Circuit Diagram: The schematic is so simple using only few components so you can make this circuit in some minutes if all parts available with you. The circuit is using low dropout regulator IC LM7805 which is easily available in the market and it is also very cheap. The circuit takes voltage from 9V battery and step down the voltage in to a DC 5V output.