Showing posts with label an. Show all posts
Showing posts with label an. Show all posts
Saturday, September 20, 2014
DRM Direct Mixer Using an EF95 6AK5
This hybrid DRM receiver with a single valve and a single transistor features good large-signal stability. The EP95 (US equivalent: 6AK5) acts as a mixer, with the oscillator signal being injected via the screen grid. The crystal oscillator is built around a single transistor. The entire circuit operates from a 6-V supply. The receiver achieves a signal-to-noise ratio of up to 24 dB for DRM signals. That means the valve can hold its own against an NE612 IC mixer. The component values shown in the schematic have been selected for the RTL2 DRM channel at 5990 kHz. That allows an inexpensive 6-MHz crystal to be used. The input circuit is built using a fixed inductor. Two trimmer capacitors allow the antenna matching to be optimized. The operating point is set by the value of the cathode resistor. The grid bias and input impedance can be increased by increasing the value of the cathode resistor. However, good results can also be achieved with the cathode connected directly to ground.
Read More..
Saturday, August 23, 2014
Making a Solar Energy Powered an iPhone Battery Charger
The project was termed as Mighty Minty Boost as it was developed to function as iPod/iPhone charger with solar power. Aside from being small, it has a large battery capacity of 3.7V at 2000mAh and it accepts input power from 3.7V to 7V. As shown in the images below, it can become a compact USB power supply when the solar cell is removed after charging. The Velcro is used to secure the Mighty Minty Boost inside a backpack or messenger bag after unplugging the solar cell.
For faster charging, a larger solar cell can be attached to the bag. Enough power can be generated to fully charge an iPhone in about 5.5 hours and an iPod Touch in 4 hours using a slightly larger solar cell with 6V at 250mAh. The charger will automatically switch to trickle charging when the cell reaches full charge. The charging current is limited to 100mA when charging using the mini USB port and the charging is limited to 280mA when charging using the barrel plug jack
![Hacks]()
.
The materials needed to build the charger include a small solar cell, Lithium Polymer battery charger, minty boost kit, adhesive backed Velcro, Altoids tin, connector/wire, and small double adhesive squares as shown in the images below. An input power that ranges from 3.7V to 7V maximum can be accepted by the single cell Lithium Polymer. In bright sunlight, the solar cell maxes out at approximately 5V at 100mA. A larger solar cell with 6V at 250mA can be used for faster charging.
![Hacks]()
The images below show the assembly of minty boost kit where a JST connector is soldered to the minty boost PCB instead of connecting the battery holder in the kit. The minty boost schema is allowed to connect to the Lithium Polymer battery charger schema with this tiny connector. The minty boost is tested by connecting the battery pack and the charger schema, the Lithium Polymer battery connects to the connector marked GND on the charger board and the minty boost connects to the connector marked SYS.
![Hacks]()
To fit the charger, a notch is cut out of the other side of the Altoids tin and used double sided adhesive to secure the charging schema to the bottom of the Altoids as shown below. The bottom of either one of the schema boards should not touch the bottom of the Altoids tin while reconnecting the minty boost PCB and the battery to the charging schema.
![Hacks]()
Connecting or adding the solar cell can be done in different ways. Shortening the connector leads and plugging the barrel plug into the barrel jack on the charging schema is one way. The other method is using another JST connector to replace the connector and plugging it into the third connector marked 5V on the charging schema. Since there is no bog barrel plug sticking out of the side of the tin, using the second method is cleaner.
As shown in the photos below, some 2” Velcro was used to attach the solar cell to the top of the Altoids. To help protect the battery, a layer of clear packing tape was used for wrapping. N top of the two schema boards, the battery pack is then set down. A red LED on the charger board will light up when the Mighty Minty Boost is set out in the bright sun. The iPod/iPhone/USB powered device can be connected once it is fully charged.
![Hacks]()
For faster charging, a larger solar cell can be attached to the bag. Enough power can be generated to fully charge an iPhone in about 5.5 hours and an iPod Touch in 4 hours using a slightly larger solar cell with 6V at 250mAh. The charger will automatically switch to trickle charging when the cell reaches full charge. The charging current is limited to 100mA when charging using the mini USB port and the charging is limited to 280mA when charging using the barrel plug jack
.
The materials needed to build the charger include a small solar cell, Lithium Polymer battery charger, minty boost kit, adhesive backed Velcro, Altoids tin, connector/wire, and small double adhesive squares as shown in the images below. An input power that ranges from 3.7V to 7V maximum can be accepted by the single cell Lithium Polymer. In bright sunlight, the solar cell maxes out at approximately 5V at 100mA. A larger solar cell with 6V at 250mA can be used for faster charging.
The images below show the assembly of minty boost kit where a JST connector is soldered to the minty boost PCB instead of connecting the battery holder in the kit. The minty boost schema is allowed to connect to the Lithium Polymer battery charger schema with this tiny connector. The minty boost is tested by connecting the battery pack and the charger schema, the Lithium Polymer battery connects to the connector marked GND on the charger board and the minty boost connects to the connector marked SYS.
To fit the charger, a notch is cut out of the other side of the Altoids tin and used double sided adhesive to secure the charging schema to the bottom of the Altoids as shown below. The bottom of either one of the schema boards should not touch the bottom of the Altoids tin while reconnecting the minty boost PCB and the battery to the charging schema.
Connecting or adding the solar cell can be done in different ways. Shortening the connector leads and plugging the barrel plug into the barrel jack on the charging schema is one way. The other method is using another JST connector to replace the connector and plugging it into the third connector marked 5V on the charging schema. Since there is no bog barrel plug sticking out of the side of the tin, using the second method is cleaner.
As shown in the photos below, some 2” Velcro was used to attach the solar cell to the top of the Altoids. To help protect the battery, a layer of clear packing tape was used for wrapping. N top of the two schema boards, the battery pack is then set down. A red LED on the charger board will light up when the Mighty Minty Boost is set out in the bright sun. The iPod/iPhone/USB powered device can be connected once it is fully charged.
Thursday, August 21, 2014
SP How to Make an AVR Perform Multiple Tasks
This article describes a way to create an AVR perform multiple tasks. Beginners who want to urge an in-depth information in AVR assemble language programming will seek this project. The assembly language helps to utilize all the functions and capabilities of the processor. browse on to grasp a lot of.
The most vital and major functionality of an operating system is performing multiple tasks on the CPU. whats being done here is time sharing multitasking which too on an AVR. An Atmega32 is ready up to perform Round-Robin Multitasking. Quasi-parallel execution of multiple tasks is feasible through Round-Robin Multitasking. The tasks are time-sliced and dont seem to be tired parallel.
The project demonstrates how the switching mechanism is finished between seven individual tasks. The RAM is split between the amount of processes that are running. A timer is employed here and a trigger is executed when it reaches a compare worth. the required registers are pushed onto the stack.
Now comes the method of switching between the varied tasks. A backup of the present stack pointer is needed as this helps to spot the previous task that was being executed. concerning fifty bytes of memory is formed offered to store the task index. this is often the stack pointer backup table.
Now suppose, task one is interrupted by the timer, the CPU registers and also the standing registers are pushed. The task index is checked at this time and also the stack pointer of future task is currently obtained. currently this task starts executing and this continues for a number of microseconds till its interrupted. This cycle continues and this provides an effect that every one tasks are being performed parallely.
Subscribe to:
Posts (Atom)
