Spy Camera Solar Power Box Circuit Diagram

 Battery life has always been a critical consideration for most of the electronic gadgets and equipment. When we talk about spy  cameras,  which  normally  function  round-the-clock, they often run out of power within a few days.  Many spy cameras (CCTV cameras) are powered by 9V PP3 type batteries that offer five times more energy  than the regular 9V alkaline battery.

Mini CCTV cameras also accept 6-12V DC supply from AC mains adaptor through the DC IN jack. AC mains adaptor for the camera increases the capacity of the 9V PP3 battery but is bulky and noisy. Whether disposable  or rechargeable batteries, making frequent replacement or recharging them is a cumbersome job. The unique solar power box described here serves an alternative solution to the problem.

Spy Camera Solar Power Box Circuit Diagram

 The circuit of the solar power box is simple. It contains a  battery charger and a battery health indicator and  a few other components.  As shown in the circuit,  DC supply available from  the solar panel (SP1) is  directly applied to the in-put of the circuit through  a protection diode (D1).  This diode is used to pre-vent  the  reverse  current  flow from the battery to  the  solar  panel  during  night. Thus, D1 allows  the current to flow from the solar panel  to the battery only. Low-voltage-drop  type 1N5817 diode is perfect for the  job.

At the heart of the circuit is an integrated current source, realised using a  popular 3-pin adjustable voltage regulator LM317T(IC1). This IC is designed  to adjust its internal resistance between  the In (pin 3) and Out (pin 2) terminals  to maintain a constant voltage of 1.25V  between the Out (pin 2) and Adj (pin 1) terminals. Here, a 9V, 280 mAh  rechargeable PP3 type Ni-MH battery  (BATT) is used as reservoir. Normally,  a charging current of about 10 per cent  of  ampere-hour  rating  is  safe  for  the  battery. Resistor R1 (39-ohm, 0.5W),  connected between pin 1 and 3 of IC1,  limits  the  charging  current  to  about  30 mA. DC output from the battery is  available at output jack J2. Red LED  ( LED1) is used as a battery ‘health’  indicator. Switch S1 is used to start the  charging while S2 is used for connect-ing the load. Note that suitable heat  sink should be used for the IC1.

The proper selection of solar panel  is important but not critical. A miniature 12V type solar panel with a cur-rent output of about 100 mA can be  used. Even if you have a solar panel  with  higher  voltage  rating,  it  will  not  create a problem as the circuit ensures  that the charging current cannot exceed  the predetermined value.

The circuit can be easily assembled  on a general-purpose PCB and housed  in a small plastic cabinet.

Sourced by: Streampowers

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TV Audio Video Transmitter Schematic Diagram

This is a simple TV audio video transmitter circuit can be constructed using this schematic diagram . This TV audio video transmitter circuit can be used to transmit video signals from VCR ( or some other device ) to a TV without using any cable .

Video signals input at jack J1 are first terminated by resistor R6 and coupled through capacitor C1 to clamping-diode D1. Potentiometer R3 is used to set the gain of the video signal; its effect is similar to that of the contrast control on a TV set.

TV audio video transmitter Schematic Diagram

Bias-control R7 can be used to adjust the black level of the picture so that some level of signal is transmitted, even for a totally dark picture.

RF-transformer T1 and its internal capacitor form the tank circuit of a Hartley oscillator that's tuned to 4.5 megahertz. Audio signals input at J2 are coupled to the base of Q3 via C2 and R4: the audio signal modulates the base signal of Q3 to form an audio subcarrier that‚s 4.5-megahertz higher than the video-carrier frequency.

The FM modulated subcarrier is applied to the modulator section through C5 and R9.
Resistor R9 adjusts the level of the subcarrier with respect to the video signal.

Transistors Q1 and Q2 amplitude modulate the video and audio signals onto an RF-carrier signal. The operating frequency is set by coil L4, which is 3.5 turns of 24- gauge enameled wire on a form containing a standard ferrite slug.

The RF output from the oscillator (L4, C7 and C9 ) section is amplified by Q5 and Q6, whose supply voltage comes from the modulator . Antenna matching and low-pass filtering is performed by C12, C13, and L1.

Resistor R12 is optional; it is added to help match the output signal to any kind of antenna.
To align this audio video transmitter you need to tune a TV receiver to an unused channel between 2 and 6. The TV must have an indoor antenna connected directly to it; an outdoor antenna or cable won't work. Make sure both potentiometers (R3, R7) are in middle position and apply power to the transmitter. Adjust L4 with a nonmetallic tool until the TV screen goes blank ,then fine-adjust L4 for the "most-blank" picture.
Connect the video and audio outputs from a VCR(AV source) to jacks J1 and J2 (respectively) of the transmitter .

After that you should see a picture on the TV screen: if you do, readjust L4 for the best picture; if you don't, check the board for any bad connections. Next, adjust R3 for the best picture brightness and R7 for the best overall picture.

Finally, adjust T1 with a nonmetallic tool for the best sound .
The TV transmitter combines line level audio and video signals, and transmits the resulting signal up to 300 feet. The circuit can be powered from a 9-12V power supply circuit .

Sourced by: circuitsprojec

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TV audio video transmitter Schematic Diagram

This is a simple TV audio video transmitter circuit can be constructed using this schematic diagram . This TV audio video transmitter circuit can be used to transmit video signals from VCR ( or some other device ) to a TV without using any cable .

Video signals input at jack J1 are first terminated by resistor R6 and coupled through capacitor C1 to clamping-diode D1. Potentiometer R3 is used to set the gain of the video signal; its effect is similar to that of the contrast control on a TV set.

TV audio video transmitter Schematic Diagram

Bias-control R7 can be used to adjust the black level of the picture so that some level of signal is transmitted, even for a totally dark picture.

RF-transformer T1 and its internal capacitor form the tank circuit of a Hartley oscillator that's tuned to 4.5 megahertz. Audio signals input at J2 are coupled to the base of Q3 via C2 and R4: the audio signal modulates the base signal of Q3 to form an audio subcarrier that‚s 4.5-megahertz higher than the video-carrier frequency.

The FM modulated subcarrier is applied to the modulator section through C5 and R9.
Resistor R9 adjusts the level of the subcarrier with respect to the video signal.

Transistors Q1 and Q2 amplitude modulate the video and audio signals onto an RF-carrier signal. The operating frequency is set by coil L4, which is 3.5 turns of 24- gauge enameled wire on a form containing a standard ferrite slug.

The RF output from the oscillator (L4, C7 and C9 ) section is amplified by Q5 and Q6, whose supply voltage comes from the modulator . Antenna matching and low-pass filtering is performed by C12, C13, and L1.

Resistor R12 is optional; it is added to help match the output signal to any kind of antenna.
To align this audio video transmitter you need to tune a TV receiver to an unused channel between 2 and 6. The TV must have an indoor antenna connected directly to it; an outdoor antenna or cable won't work. Make sure both potentiometers (R3, R7) are in middle position and apply power to the transmitter. Adjust L4 with a nonmetallic tool until the TV screen goes blank ,then fine-adjust L4 for the "most-blank" picture.
Connect the video and audio outputs from a VCR(AV source) to jacks J1 and J2 (respectively) of the transmitter .

After that you should see a picture on the TV screen: if you do, readjust L4 for the best picture; if you don't, check the board for any bad connections. Next, adjust R3 for the best picture brightness and R7 for the best overall picture.

Finally, adjust T1 with a nonmetallic tool for the best sound .
The TV transmitter combines line level audio and video signals, and transmits the resulting signal up to 300 feet. The circuit can be powered from a 9-12V power supply circuit .

Read More