An IR Encoder/Decoder pair made with PIC12C508's for each of them

I volunteered to turn a friend of mine's Warhammer 40K Imperial Rhino personel carrier into a remote controlled item. Little did I understand the undertaking that I had agreed on! My requirements for this project were that the transmitter and receiver had to be a single chip design, done all in software. I succeeded. The receiver chip uses a Panasonic 4602 38KHz receiver and that's it for external components. It has the serial input (GP3) , two RC hobby servo outputs (GP0/GP1) and three digital outputs (GP2,4,5). Here is the code for the receiver chip. It is a bit of a specialty in that the digital outputs are actually "momentary contact" type outputs because I only needed a pulse to go out to trigger a cheap sound board I got from a $6 toy! I don't even use the GP2 output in this design. The receiver uses 4 NiCd 115MAH cells, the largest set I could fit into the Rhino! The transmitter chip uses 5 pullup resistors and an IR LED powered through a 330 resistor - quite a bit of power I think. To keep things simple, I used a 78L05 to power the PIC so I could use a 9V battery and keep the whole project box size small. It will run fine on 3 alkaline cells, or, from 4.5 to 5.5V. The transmitter reads the status of the 5 momentary contact buttons and decides what messages to send to the receiver. Here, I give priority by bit value, just so there needs to be no encoding and it keeps the code simple. Also, when a direction command is given (forward, reverse, left, right) I also give the 'go' command and the 'motor noise' commands. If a button is pressed and immediately released, the transmitter waits a couple seconds and sends the 'stop' command. This allows you to hold a button down, issue a series of commands continuously but still stop nicely. The transmitter issues a constant stream of 'stop' commands when no button is pressed. This is a nice troubleshooting method as well as insuring that the unit doesn't just take off! Here is the code for the IR transmitter.

Building the Rhino was a challenge. It is about 5 inches long and about 3.5 inches wide and about 2 inches tall. Into that I needed to put a battery pack, two motors, two motor drivers, the IR receiver board and actual drive wheels and wiring with a sound board and speaker. Wow. I used two LEGO micro motors for the drive motors, they were connected to two LEGO medium pulleys via rubber bands and held in place using two-stud LEGO axels through a two stud Technic rail - If you know LEGO, you know what I mean by that. I drove the motors by connecting them to the "guts" of two old hobby servos. This gave me two small bi-directional motor drivers that I only needed a single I/O line to control. The receiver board was about 1 inch by 1.5 inches and had the IR receiver sticking out the top of the model. The 4 cell 115MAH NiCd pack was about 1 inch x 2 inch by 0.5 inch, very small! I used "tank" steering and mounted a pivot ball near the back of the tank to lower friction. Below are the schematics for the transmitter and receiver sections including the battery and motor/driver setups as I installed them. I only needed to make a couple of smalll internal mods to get all of the stuff to fit.

Making a simple effective whisker bumper

We all have need of that last line of defense when the SONAR glitches, the IRPD doesn't and our bot is on a collision course with a table leg. That last defense against re-kitting is a bumper. I have made a few from microswitches, miniswitches and other things - usually they work, sometimes they need too much force to work and "ugh" collision. This example is another type of sensor that doesn't use a switch, its parts are super cheap and it works just great. Its a "whisker" bumper. Here are the parts you need to build one too.
Small piece of single sided un-etched PC board (I use 3.5cm X 2cm)
Two lengths of 1mm piano wire bent into your appropriate shape (hopefully both the same!)
Two 2-pin "Berg" headers
A little bit of wire

Let me show you some pictures and describe what is going on, a picture is worth a thousand words in this kind of game. Click on the images to make them bigger

This is the top of the PC board with mounting holes drilled.

Note centering of the two Berg headers and the whiskers

so they go directly between the leads. This side of the

board is NON conductive! It is about 1.5cm between

the point where the wire goes through the board and

the Berg headers. I pulled the plastic separator off to

install the whiskers then put is back on loosely, mostly

for looks I guess.

I have carved out two places for the contacts and then

shorted the two of them together with a wire. You could

have two different inputs here if that is needed. The wires

each have a 'Z' bend in them where they are soldered to

the large conductive surface, this gives better support

than just running the wires through.

for more information click here

on chip LDO with adaptive control

Low-dropout linear regulators (LDOs) have gained popularity with the growth of battery-powered equipment. Portable electronic equipment including cellular telephones, laptop computers and a variety of handheld electronic devices has increased the need for efficient voltage regulation to prolong battery life. LDOs are widely built into all electronic appliances by all means not only for portable electronic devices. Recently, in order to save power consumptions, a system that was originally supplied by one LDO is divided into many blocks and supplied by a plurality of LDO. This means that the power is supplied only to an operating block and unused blocks are made into a standby mode. So the power consumption can be saved for a full system

 

In this work, a quick response circuit is proposed to improve the load transient response of a fully On Chip Low Dropout Voltage Regulator, which is operable with very low power consumption for use in digital baseband of cell phones was developed. The quick response circuit consists of two high speed offset comparators working in tandem with respect to the load variations. The high speed comparators were incorporated into the fast path of the circuit thereby making the fast path loop adaptive to the changes in the load transient. This was a major reason we could reduce the power consumption as the fast path was connected to the circuit only when there is a change in the load variations. The stability of the system was ensured by compensating the circuit at no load conditions. The circuit was made temperature and process independent by the use of an advanced bias circuit. The circuit was designed for a specification of 1.2V, 50mA. A line and load regulation of 30ppm/mA and 0.01% respectively was achieved. The transient overshoots and undershoots were in the range of few tens of millivolts. The circuit was satisfactorily working for temperature ranges from -55oC – 125oC. This makes the circuit comparable to the industry standards. The work was carried on CADENCE Spectre simulations with 180nm UMC CMOS technology and it showed that transient responses with less transients overshoots and undershoots, when driving large current loads, could be achieved. for more information click  link

http://www.projectguidance.com/

Project : Infrared Remote Control

This circuit will allow you to turn on any piece of equipment that operates on 115 volts ac. The receiver circuit is based on the Radio Shack infrared receiver module (MOD), part number 276-137. It is also available from some of the other sources listed on my Links page. The MOD accepts a 40khz IR signal that is modulated at 4 khz. When a signal is received the MOD will go low. The sensitivity of the MOD is set by different values for R1 and C1. The values for R1 may need to be as high as 10,000 ohms and for C1 40uf. This will prevent the unit from turning on under normal lighting conditions. You will need to experiment with the values that work best for you. The output of the 4013 chip a flip flop toggles on and off with the reception of a IR pulse. The output of the 4013 turns on the MOC optical coupler which in turn switches on the triac and supplies power to the AC load.