Project Solutions (2011/07/26)
Index
Kitchen Table
Published:2011/7/26 22:03:00 Author:Phyllis
By Prof. Dr. Martin Ohsmann Low-Power LED Flash powered by lemon juice This circuit will need just a few micro-amps to make an LED flash. The energy comes from a home made ’vegetarian’ battery. We have to admit that the circuit shown in Figure 1 appears a bit over the top for an on/off indicator, as the same functionality could have been achieved from a clas... (View)
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Parallel Port Mains Switching Interface--switch radio controlled mains sockets on and off from a PC （2）
Published:2011/7/26 21:57:00 Author:Li xiao na
by K. Heiden Interface Circuit The parallel port interface circuit (Figure 3) is essentially divided into two parts: the part that drives the remote control transmitter using optocouplers, and two optional extra switching stages built around IC1 and two relays. This switching circuit allows for the control of two additional devices, located near to the PC, directly ... (View)
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Of Mice and Light
Published:2011/7/26 21:43:00 Author:Phyllis
increased accuracy without mechanics By Harry Baggen These days, no one is surprised any more about a mouse without a ball, although optical mice have been around for only a few years. Meanwhile, optical sensors have evolved to the point where they can easily compete with the accuracy of a mechanical assembly. In fact, they are often even more accurate and react quicker. ... (View)
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Parallel Port Mains Switching Interface--switch radio controlled mains sockets on and off from a PC （1）
Published:2011/7/26 21:41:00 Author:Li xiao na
by K. Heiden The wide availability of low-cost switched mains sockets with radio remote control provides a simple way to control electrical equipment, lights, etc. using a PC. Using radio not only means that we do not need a cable, but also avoids problems with electrical safety as the interface is electrically isolated from the mains supply. As USB interfaces becom... (View)
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Touch-controlled switch--With a PIC
Published:2011/7/26 21:19:00 Author:Li xiao na
Design by J. Wickenhauser You don’t need special ICs when a capacitive (or ’touch’) switch can also be realized with an inexpensive PIC controller. This article shows how it’s done. Over the past few years several manufacturers have come up with special integrated circuits for touch control switches. These ICs usually operate on the principle of capacitive change, w... (View)
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2 Transistors, 1 Crystal — that＇s it!
Published:2011/7/26 21:19:00 Author:Phyllis
Poor Man’s DRM is here By Burkhard Kainka Almost too good to be true but tried & tested: a totally undemanding receiver giving you an opportunity to experience DRM digital broadcasts on shortwave. Digital SW almost for free! There are a large number of shortwave stations broadcasting not only conventional a... (View)
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Through-hole plating double-sided PCBs
Published:2011/7/26 21:06:00 Author:Phyllis
Making a double-sided PCB is far from easy. It is quite a task to make sure that the artwork films with the tracks and pads are perfectly aligned on both sides. And it becomes even more difficult when both sides have to be connected at various points. The professional PCB manufacturer uses through-hole plating: the board is drilled and a thin layer of copper is deposited in the holes that require a connect... (View)
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Foil Capacitor Polarity--Which terminal of a foil capacitor acts as the screen?
Published:2011/7/26 21:02:00 Author:Li xiao na
By H. Friedli As most of you will be able to confirm, an electrolytic capacitor has to be connected the right way around in an electronic circuit. If you get the connections wrong, the innards of the capacitor will greet you when the power is switched on — the capacitor can will rupture, spilling its liquid or partly vaporised contents across the circuit board or (in the case of older high-... (View)
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Repairing the damage caused by leaking batteries
Published:2011/7/26 20:59:00 Author:Phyllis
Most of you will have suffered from this at one time or another: a torch or other battery-powered equipment has been neglected too long and the batteries started leaking. After all, these cells contain a cocktail of corrosive chemicals that will eventually find their way through the battery housing and end up in all those places where they’re not wanted. NiCad cells that are overcharged can vent the electrolyte in ... (View)
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Simple l2V to 230V Power Inverter--A mobile power outlet（4）
Published:2011/7/26 20:43:00 Author:Li xiao na
Design by G. Gerards Construction The design of the printed circuit board is shown in Figure 4. Despite large ground areas and wide tracks it may be necessary to strengthen the tracks carrying the transformer current by tinning them. It is recommended to start by mounting the AMP (’fast-on’) lugs (spade terminals), because they require considerable force to insert i... (View)
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Everything You Need to Know to Drive a Stepper Motor （3）
Published:2011/7/26 4:13:00 Author:Amy
By Horst Huber Hardware Now that we have determined what the properties of the motor are, we have to choose the right hardware. But don’t panic, we’ll work through this in a few simple steps as well. Our driver stage has several limitations. The maximum operating voltage is 18 V (preferably a bit less, such as 15 V) and the maximum motor current is 2 Am... (View)
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Everything You Need to Know to Drive a Stepper Motor （2）
Published:2011/7/26 3:48:00 Author:Amy
By Horst Huber 2. Connections Once you have determined what type of motor you have, it’s time to find out which leads belong to each of the windings. Measure the resistance between the connections using a multi-meter. Go through all possible combinations and make a note of the results. The resistance between the ends of a winding will be low. Between the centre t... (View)
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Everything You Need to Know to Drive a Stepper Motor (1)
Published:2011/7/26 3:31:00 Author:Amy
By Horst Hubert First steps Stepper motors have found their way into Elekfor Electronics many times, most recently in the November and December 2003 issues. In contrast to previous articles, well keep it practical and won’t go into the theory. If you want to know more about the background, have a look at some previous articles (listed in the reference section at the end of this arti... (View)
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Wind Speed & Direction Meter with a Clever Touch （4）
Published:2011/7/26 2:56:00 Author:Amy
G.Samblancat Amplifier adjustments The first thing you need to do after switching on the supply voltage is adjust the four multitum presets P1-P4. Your goal will be to make the ICla and IClb output signals cover the full range of 0.5 V to 4.5 V. This may be done with the aid of either an oscilloscope or the TUNE software. In the first case you closely watch the... (View)
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Wind Speed & Direction Meter with a Clever Touch （3）
Published:2011/7/26 2:31:00 Author:Amy
G.Samblancat Building it Figure 4 shows the component overlay. The copper track layout may be found on the PCB Layout pages towards the back of this issue. The board consists of a main section and a sensor section. The elongated shape of the board allows it to be mounted in a 32-mm PVC tube, just under the sensor part. Note that presets P1-P4 are accessible from t... (View)
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Wind Speed & Direction Meter with a Clever Touch （2）
Published:2011/7/26 2:04:00 Author:Amy
G.Samblancat Block diagram No remarkable things are seen in the block diagram in Figure 2. The starting point is the pair of Hall sensors arranged at an angle of 90 degrees. Two amplifiers, one for each sensor, condition the sensor signals for use by an ADC and then on to the processor. The ‘limiter’ block pr... (View)
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The XC9215/16/17 Series Synchronous-Rectification Type Step-Down DC-DC Converters
Published:2011/7/26 1:57:00 Author:Phyllis
The XC9215/16/17 series of synchronous-rectification type step-down DC-DC converters, which are in USB-6B (2.0×1.8×0.88mm) package, are an ideal choice for noise sensitive RF applications. These highly integrated DC-DC converters can realize a stable power supply with 400 mA output current with a built-in 0.5-_ P-channel driver transistor and 0.6-_ N-channel switching transistor and an externally connec... (View)
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Simple l2V to 230V Power Inverter--A mobile power outlet （3）
Published:2011/7/26 1:21:00 Author:Li xiao na
Design by G. Gerards More design thoughts The transformer for the project should be a toroidal type with a primary of 230 V and two 12-V secondary windings. Readers in countries with 110 V, 117 V or 127 V mains voltage are, of course, advised to use a matching 200-watt transformer. If you are lucky to have an old toroidal transformer lying around in a drawer or a junk box, it should... (View)
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Simple l2V to 230V Power Inverter--A mobile power outlet （2）
Published:2011/7/26 1:06:00 Author:Li xiao na
Design by G. Gerards Pulsewidth modulation The central part in the circuit is an SG3526 low-cost switch-mode regulator, which is supplied by a number of manufacturers under the component identifier xx3526, where xx is a manufacturer-specific letter combination. The 3526 supports all known switch-mode PSU topologies. Its complete datasheets may be obtained free of charge from wwvj.un... (View)
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Wave catcher （4）
Published:2011/7/26 0:54:00 Author:Phyllis
By Burkhard Kainka Fixed-frequency An alternative to a circuit with adjustable tuning is to use a fixed-frequency filter. In the medium-wave band, there is often only one usable reception frequency. Although the relative bandwidth of the input circuit is relatively large, good selectivity is possible thanks to the low frequency. A circuit such as that shown in Figure 6(View)
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