This kit gives a cheap, easily understandable and adaptable combination lock. The relay will only respond to the right sequence of four numbers keyed in on the remote keypad. Touching any other key will reset the lock. The key combination can be easily changed on the main mother board.
The kit is constructed on a single-sided printed circuit board (PCB). Protel Autotrax and Schematic were used to design the board.
Choose four numbers you want to be the secret combination. The numbers must be different. Let us choose 1357. That is, we want to touch 1 then 3 then 5 then 7 on the Remote Keypad for the relay to trigger. Touching any other number we want to reset the unit.
On the main PCB connect Pad A to one of the pads on line 1 using some of the hookup wire provided. Connect pad B to a pad on line 3, pad C to a pad on 5, pad D to a pad on line 7. Now connect the five remaining numbers to the five pads on the RESET pad.
Connect a 9 to 12V power supply. The combination lock is now ready.
A 12V relay has been provided with the kit. It can switch a main powered device such as a light. The 14013 dual D flip-flop (FF). Each 14013 contains two D flip-flops. The four FF are connected to A, B, C and D pads. ABCD gives the 4 digits which must be keyed in in sequence for the relay to trigger. The five remaining digits may be connected to the RESET PAD. If one of these digits is keyed in during the ABCD sequence then the circuit will reset.
The ABCD touch pads are connected to the clock input pins 3 and 11 of each 14013. ABCD pads are normally tied low by the 4M7 resistors. Touching the pads of each keypad briefly pulls the input high and the state of the FF is altered. The output Q pins (1 and 13) are wired so that when the correct sequence is keyed in then pin 13 of IC2 turns on the transistor.
The reset keys are all wired to the set pins (6 and 8) of each IC. $44.95 Shipping included in the US.
This kit produces a clicking sound which attracts fish. We have had customers who have reported excellent results! Features very tiny circuit board and small piezo. Operates from 9V battery (not included). Size of board only 1" x 3/4" so it can be placed in almost any watertight jar and lowered into the water. Complete with all parts, PC board and instructions.$29.95 Shipping included in the US.
Drive more safely in freezing weather. This kit uses a flashing LED to indicate a road temperature close to freezing point; below that point the LED is on continuously. A reliable temperature sensor with mounting stud is included.
$39.95 Shipping included in the US.
Mosquito Repellant Kit
This electronic circuit is able to generate 10-30KHz ultrasonic range frequency to keep mosquitoes away from the immediate vicinity. This high frequency sound irritates the insects, and will direct them to find a meal elsewhere.
Beginner, easy to assemble/solder electronic kit. $29.95 Shipping included in the US.
Sound operated switch kit New! New, in box (NIB). This module can turn on small motors or lights when it detects sound. A great security device! The kit measures 1.6"x1.2"x0.5". It requires 3V DC supply to operate. This is an easy-to-assemble kit. $19.95 Shipping included in the US.
Light Activated Switch Electronic kit New! New, in box (NIB). This module can turn on small motors or lights when it detects light. The unit measures 1.6"x1.2"x0.5". It requires 3V DC supply to operate. This is an easy-to-assemble kit. $19.95 Shipping included in the US.
This electronic circuit will transform*ADULT SUPERVISION REQUIRED FOR THIS PROJECT.
the low voltage of 9 V batteries into high
enough power for shocking effect when touched,
but will not be in the range to create any
permanent or fatal damage.
Motor speed control kit for hobby motors. This module can be used to control small motor speed from 5% to 95%. The controller measures 1.6"x1.2"x0.5". It requires 3V DC supply to operate. This is an easy-to-assemble kit.$19.95 Shipping included in the US.
An ion generator or ioniser is a device which creates ions and puts them into the air. A high negative voltage of around 5000V will make negative ions and a high positive voltage will make positive ions. There are supposed to be health and other benefits about living in an environment which has an excess of negative ions. This is a topic we will return to at the end of the documentation.
The simplest and easiest way to generate ions is to use a Cockroft-Walton multiplier circuit. This is a string of diodes and capacitors in a succession of voltages doubling circuits. The diodes and ceramic disk capacitors are readily available components with a high long term reliability.
NOTE: this project MUST be mounted in an enclosed box or container for THREE reasons:
- the first is that it is mains powered. It must be kept protected from people accidentally touching it. The mains cable must be firmly secured by the usual means.
- second, is that it has a chain of voltage doubling circuits. At the end of the chain (at C30) you do not have to touch a component to get a shock. A spark will jump across about 3mm to get you. (The shock is really just a tickle and it is more a surprise than anything else.)
- third, the final stage of the ion generator - the three resistors and the pin farm - must be suspended in the air and not near or touching a solid surface. Ions are funny things. At the high voltages but very low currents available the ions will collect on particles (dust) and solid surfaces. If the pin farm and protection resistors are on a surface (plastic, newspaper) the ions will not be generated.
Also note that if you are sitting in a well insulated, dry chair then there is no shock if you accidentally touch the pins on the pin farm when the generator is in operation. You do not have to worry that when you listen to the ions being generated that you will get a huge shock if you accidentally touch a pin. We are not suggesting you deliberately start feeling the pins. And do not touch the components in the doubling chain what ever you do.
The circuit as presented is designed to generate negative ions. However, by simply reversing all the diodes, D1 to D30, in the ladder you automatically make it into a positive ion generator. This gives you an easy way to test for yourself whether negative ions and/or positive ions affect mood, performance etc. You may buy two of these kits and construct one as a negative ion generator and the other as a positive ion generator. Then put them in different situations either with or without people knowing. Leave them on for several days and note any changes or alteration in behaviour.
ARE NEGATIVE IONS OF BENEFIT TO YOU?
Quite a bit of research has gone into this topic. Research ranges from the pseudo-scientific to the reputable. A list of some papers from the latter group is given here. In summary, there is no evidence that negative ions have any effect on well being however it is defined. The claims by commercial producers of negative ion generators that their products enhance efficiency, increase productivity and contribute to personal health are unsupported by scientific evidence. However, if you think something is going to do you good then it may in fact do so; this is the placebo effect. And a bit of research in the 1990's is going into it. But that is another story. $99.95 Shipping included in the US.
Very useful for telephones with several extensions. When connected, no one will be able to eavesdrop on you until after the receiver has been returned.
This is a beginner level, easy to assemble kit. With instructions. $39.95 Shipping included in the US.
This kit can be used in calibration, clocks, and as a time-base in circuits.
$39.95 Shipping included in the US.
|digitally cleans the video signal / removes unwanted distortion in video signal|
|stabilises picture quality and luminance fluctuations|
|improves picture quality on LCD monitors or projectors|
|S-video and composite video in- and output (S-video and composite video signals can not be mixed)|
|led indication when distorted video signal detected|
|for PAL / NTSC video|
|power supply : 9Vdc / 100mA min. (adapter required)|
|dimensions : 100 x 84mm (4.0" x 3.3")|