Posted on Tuesday, April 27, 2010 • Category:
Amplifiers
The amp is based on the Project 19 PCB, so uses a pair of LM3876 (or LM3886) power opamps, run from a ±35V supply. I used a cut-down P88 preamp PCB because I only wanted one preamplifier stage, but the entire board can also be used. Alternatively, the P19 amp can be run at higher gain than normal, alleviating the need for a preamp at all. The down side of this is that the noise level will be higher, and background noise may be audible with efficient speakers and/ or very quiet surroundings.
Posted on Tuesday, April 27, 2010 • Category:
Battery Chargers
Batwatch is a simple monitor for a solar panel battery charger, using an Atmel ATtiny13V. It periodically measures the charge current and battery voltage, and shows them by blinking two LEDs. I built this circuit into the plug of a VW solar charger panel that is used to prevent a discharge of the battery when a car is not used for some time. A modern car contains a large amount of electronics, and a quiescent current of 40-50mA (about 1Ah per day!) is considered "normal".
Posted on Tuesday, April 27, 2010 • Category:
PIC
When the device is connected to the computer, a Virtual COM Port (VCP) will be created. This is shown at the Device Manager Window under Ports(COM & LPT). In this case, COM5 was created when the PIC18F4550 was attached to the USB Port. It may be interesting to note that if you plug in your PIC in different USB ports, the VCP created will be different.
Posted on Tuesday, April 27, 2010 • Category:
AVR
This is the transmitter PLL module with ATMega8, MC145170 and 16x4 LCD Display.
Posted on Tuesday, April 27, 2010 • Category:
PIC
The quickest way to display something is probably sending the data to the computer to be displayed on the monitor. One of the ways to do this is to use the USART module on board the PIC Microcontroller by making use of the pins RC6 and RC7 which is also the TX and RX pins respectively when the SPEN bit on the RCSTA register is set.
Posted on Friday, April 23, 2010 • Category:
FM Transmitters
This PLL has been designed with an old Motorola circuit :the MC145151.
The VCO is based on a "Colpitz" oscillator equiped with a Fet Transistor.(J310)
Two varicap Diodes are used in order to reduce the global noise of the VCO.
In addition,these two diodes allow the PLL to keep the lock status through a large range of climatic conditions.
An another J310 is used in order to match the impedance between the oscillator and the fist amplifier stage.
A MSA1105 from Minicircuits increases the RF power level coming from the VCO to +14dBm.
A simple low pass filter rejects the second harmonic to -20 dB.(Worst case)
Finally, a 7 dB attenuator and a second amplifier stage (BFR96S) achieve this radio design.
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