Converting a DCM Motor Circuit Diagram

We recently bought a train set made by a renowned company and just couldn’t resist looking inside the locomotive. Although it did have an electronic decoder, the DCM motor was already available 35 (!) years ago. It is most likely that this motor is used due to financial constraints, because Märklin (as you probably guessed) also has a modern 5-pole motor as part of its range. Incidentally, they have recently introduced a brushless model. 

The DCM motor used in our locomotive is still an old-fashioned 3-pole series motor with an electromagnet to provide motive power. The new 5-pole motor has a permanent magnet. We therefore wondered if we couldn’t improve the driving characteristics if we powered the field winding separately, using a bridge rectifier and a 27 Ω current limiting resistor. This would effectively create a permanent magnet. The result was that the driving characteristics improved at lower speeds, but the initial acceleration remained the same. But a constant 0.5 A flows through the winding, which seems wasteful of the (limited) track power. A small circuit can reduce this current to less than half, making this technique more acceptable. 

Circuit diagram :

Converting a DCM Motor Circuit Diagram

The field winding has to be disconnected from the rest (3 wires). A freewheeling diode (D1, Schottky) is then connected across the whole winding. The centre tap of the winding is no longer used. When FET T1 turns on, the current through the winding increases from zero until it reaches about 0.5 A. At this current the voltage drop across R4-R7 becomes greater than the reference voltage across D2 and the opamp will turn off the FET. The current through the winding continues flowing via D1, gradually reducing in strength. When the current has fallen about 10% (due to hysteresis caused by R3), IC1 will turn on T1 again. The cur-rent will increase again to 0.5 A and the FET is turned off again. This goes on continuously.

The current through the field winding is fairly constant, creating a good imitation of a permanent magnet. The nice thing about this circuit is that the total current consumption is only about 0.2 A, whereas the current flow through the winding is a continuous 0.5 A. 

We made this modification because we wanted to convert the locomotive for use with a DCC decoder. A new controller is needed in any case, because the polarity on the rotor winding has to be reversed to change its direction of rotation. In the original motor this was done by using the other half of the winding.

There is also a good non-electrical alter-native: put a permanent magnet in the motor. But we didn’t have a suitable magnet, whereas all electronic parts could be picked straight from the spares box. 

Author : Karel Walraven

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Simple Wire Loop Game Circuit Diagram

In the ‘Wire Loop Game’, a test of dexterity,  the player has to pass a metal hoop along a  twisted piece of wire without letting the hoop  touch the wire. Usually all the associated electronics does is ring a bell to indicate when the  player has lost. The version described here has  a few extra features to make things a bit more  exciting, adding a time limit to the game and a ticking sound during play. 

Two 555 timer ICs are used to provide these  functions. IC1 is configured as a monostable which controls the time allowed for the  game, adjustable using potentiometer P1. IC2  is a multivibrator to provide the ticking and Two 555 timer ICs are used to provide these  functions. IC1 is configured as a monostable which controls the time allowed for the  game, adjustable using potentiometer P1. IC2  is a multivibrator to provide the ticking and he continuous buzz that indicates when the  player has touched the wire with the hoop. 

Wire Loop Game Circuit Diagram

When the monostable is in its steady state,  the output of IC1 (pin 3) is low. T1 acts as  an inverter, and D2 is thus forward biased.  R8 and R4 are therefore effectively in parallel, with the result that IC2 produces a low audible tone. The value of R4 is considerably  greater than that of R8, and so the frequency  of the buzz generated by IC2 is chiefly deter-mined by the value of R8.

When the monostable is triggered, the high  level at the output of IC1 is again inverted  by T1. D2 is reverse biased and so R8 is effectively removed from the circuit. The frequency of IC2 is now largely determined by  the value of R4. The ratio of R4 to R5 and the  value of C4 affect the mark and space periods for the multivibrator: for a satisfactory  ticking sound short pulses with long gaps  between work well. 

Whether a sound is produced also depends  on the voltage on pin 4 of IC2. When the 9 V  supply is connected the monostable is initially inactive and there is no voltage across  C1. Pin 4 (reset) on IC2 is thus low and no tone  is produced. IC1 is activated by a brief press of  S1, which generates a low-going trigger signal  on pin 2 to start the game. C1 now charges via  D1 and IC2 is allowed to oscillate, generating  the ticking sound. 

The pulse width of the monostable sets the  game duration, and can be adjusted using  P1. If the allowed time expires, or if the reset  input to IC1 is taken low (which happens when the hoop touches the wire), the monostable  returns to the quiescent state. This causes IC2  to generate the low buzz sound. D1 is now  reverse biased and C1 discharges through the  relatively high-valued resistor R9. After a few  seconds the voltage across C1 falls sufficiently  that the buzz stops and the circuit is ready for  the next player. 

The circuit can be built first on a breadboard,  so that the component values can easily be changed to suit particular preferences for  game duration and buzz pitch. When suitable  values have been selected the circuit can be  built more permanently on a printed circuit  board. The author used a sheet of plywood  to form a base for the game, the twisted wire  being fixed to the board and wired to the electronics mounted below it. 

Author: Andreas Binner

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Controlling a Mazda Car Using an iPhone

This hack illustrates how a car can be controlled from anywhere in the world by tapping into the disgnostic systems and onboard webserver of the car. The objective is to keep the car “live” and connected to the Internet 24×7 even when not being driven. It should run continuously without flattening the car battery by critically selecting a low-power computer. Also, the user should be able to start the engine, pop the trunk, lock/unlock, and view all vehicle diagnostics from his iPhone. The chosen car was a Mazda RX-8 as shown in the image below. It was released in 2004 and consists of 6-speed manual transmission with a 1.3L 13B-MSP RENESIS engine.

The computer used in this hack is an Alix-1 which draws very little power but is fast enough to run a full Linux distribution system. To fit into a recess in the base of the RX-8 boot, a mounting frame was assembled. It has room to mount the Alix-1, a USB hub, a charge circuit, and a deep-cycle 28A/h sealed lead acid battery. The SLA battery is charged using an intelligent battery charger so it can continuously run the Alix-1. Whenever the car is running, the charger tops it up. The charger works perfectly in this application although it was designed for topping up deep-cycle batteries. Shown in the image below is the Alix-1 mounted in a custom subframe inside the boot of RX-8.

To run diagnostics on the engine management system, a laptop is usually plugged by a mechanic to the On-Board Diagnostics (OBD) port under the dash. The Alix-1 is permanently connected to the port on this RX-8 and dozens of parameters about vehicle performance including speed, RPM, intake manifold temperature, engine load, fuel level, fuel pressure, fuel injection mode, timing and many other items are polled to the ECU every few seconds. A MySQL database is used to store all data indefinitely. Shown in the photo below in a conference where the integration of the Alix-1 with the existing electronics was explained.

To be able to access the car for remote diagnostics, it should be continuously connected to the Internet. The Alix-1 is allowed to have software control of engine start/stop, accessory power, door lock/unlock, and boot release by building a custom ignition manager based on an Arduino development board. Through Wi-Fi, it allows authorized laptops to associate with it to access vehicle management functions directly since the car acts as a mobile access point.

The GPS values were stored using a USB GPS receiver that allows the data logging system. It has every set of engine management parameters which can be used to match engine events to locations, generate tracks showing previous journeys, or display direction information. The back right window of the car has a mounted RFID reader which unlocks the car and starts the engine automatically when it detects an authorized FRID tag. The RFID implant being used to unlock the front door of the house is demonstrated in the video below.

A password-protected web interface optimized for full-screen display on an iPod Touch or iPhone running the SOPODS full screen web browser is provided by the webserver of the car. The 3 screens of the web nterface include Control, Telemetry, and Location. The web interface accessed from an iPod Touch is briefly demonstrated in the video below. A more professional version was created on the next video.

For the audio system, the Alix-1 is allowed to inject audio directly into it by modifying the BOSE head unit shown in the below image. The head unit was opened up and soldered input leads to the CD player circuit board since the BOSE sound system in the RX-8 has no “line in” connection. Connected through the head unit was the headphone output from the Alix-1. Any sound played by the Alix-1 is injected into the head unit when the CD is selected. Through the existing sound system, the Alix-1 can play music and issue voice alerts.

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Simple Soldering Iron Tip Preserver Circuit Diagram

Simple Soldering Iron Tip Preserver Circuit Diagram. Although 60/40 solder melts at about 200&degC, the tip temperature of a soldering iron should be at about 370&degC. This is necessary to make a good quick joint, without the risk of overheating delicate components because the iron has to be kept on the joint for too long. Unfortunately, at this temperature, the tip oxidises rapidly and needs constant cleaning. That's where this circuit can help - it keeps the soldering tip to just below 200&degC while the iron is at rest. Oxidisation is then negligible and the iron can be brought back up to soldering temperature in just a few seconds when needed. In addition, normal soldering operation, where the iron is returned to rest only momentarily, is unaffected because of the thermal inertia of the iron. Two 555 timers (IC1 & IC2) form the heart of the circuit.

Simple Soldering Iron Tip Preserver Circuit Diagram

Soldering Iron Tip Preserver Circuit Diagram

IC1 is wired as a monostable and provides an initial warm-up time of about 45 seconds to bring the iron up to temperature. At the end of this period, its pin 3 output switches high and IC2 (which is wired in astable configuration) switches the iron on - via relay RLY1 - for about one second in six to maintain the standby temperature. The presence of the iron in its stand is sensed by electrical contact between the two and some slight modification of the stand may be necessary to achieve this. When the iron is at rest, Q1's base is pulled low and so Q1 is off. Conversely, when the iron is out of its stand, Q1 turns on and pulls pins 2 & 6 of IC2 high, to inhibit its operation. During this time, pin 3 of IC2 is low and so the iron is continuously powered via RLY1's normally closed (NC) contacts. Note that the particular soldering iron that the circuit was designed for has its own 24V supply transformer. Other irons may need different power supply arrangements. The warm-up time and standby temperature can be varied by altering R2 and R5, as necessary.

Author: Alan March - Copyright: Silicon Chip Electronics

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Project of Whistling Kettle Circuit Diagram

Most electric kettles do not produce a whistle and just switch off when they have boiled. Fitting a box of electronics directly onto an electric kettle (or even inside!) to detect when the kettle has boiled is obviously out of the question. The circuit shown here detects when the kettle switches off, which virtually all kettles do when the water has boiled. In this way, the electronics can be housed in a separate box so that no modification is required to the kettle. The box is prefer-ably a type incorporating a mains plug and socket. 

In this application, the current flowing in coil L1 provides a magnetic field that actuates reed switch S1. Since the current drawn by the kettle element is relatively large (typically 6 to 8 amps), the coil may consist of a few turns of wire around the reed switch. The reed switch is so fast it will actually follow the AC current flow through L1 and produce a 100-Hz buzz. The switching circuit driven by the reed switch must, therefore, disregard these short periods when the contacts open, and respond only when they remain open for a relatively long period when the kettle has switched off. 

Whistling Kettle Circuit diagram :

Whistling Kettle Circuit Diagram

 

The circuit is based on a simple voltage controlled oscillator formed around T2 and T3. Its operation is best understood by considering the circuit with junction R4/R5 at 0 V and C4 discharged. T2 will receive base current through R5 and turn on, causing T3 to turn on as well. The falling collector voltage of T3 is transmitted to the base of T2 by C4 causing this transistor to conduct harder. Since the action is regenerative, both transistors will turn on quickly and con-duct heavily. C4 will therefore charge quickly through T2’s base-emitter junction and T3. Once the voltage across C4 exceeds about 8.5 V (leaving less than 0.5 V across T2’s b-e junction), T2 will begin to turn off. This action is also regenerative so that soon both transistors are switched off and the collector volt-age of T3 rises rapidly to +9 V. With C4 still charged to 8.5 V, the base of T2 will rise to about 17.5 V holding T2 (and thus T3) off. C4 will now discharge relatively slowly via R5 until T2 again begins to conduct whereupon the cycle will repeat. The voltage at the collector of T3 will therefore be a series of short negative going pulses whose basic frequency will depend on the value of C4 and R5. The pulses will be reproduced in the piezo sounder as a tone. 

The oscillation frequency of the regenerative circuit is heavily dependent on the voltage at junction R4/R5. As this voltage increases, the frequency will fall until a point is reached when the oscillation stops altogether. With this in mind, the operation of the circuit around T1 can be considered. In the standby condition, when the kettle is off, S1 will be open so that C1 and C2 will be discharged and T1 will remain off so that the circuit will draw no current. When the kettle is switched on, S1 is closed, causing C1 and C2 to be discharged and T1 will remain off. C3 will remain discharged so that T2 and T3 will be off and only a small current will be drawn by R1. Although S1 will open periodically (at 100 Hz), the time constant of R1/C1 is such that C1 will have essentially no voltage on it as the S1 contacts continue to close. 

When the kettle switches off, S1 will be permanently open and C1/C2 will begin to charge via R1, causing T1 to switch on. C3 will then begin to charge via R4 and the falling voltage at junction R4/R5 will cause T2/T3 to start oscillating with a rising frequency. However, once T1 has switched off, C3 will no longer be charged via R4 and will begin to discharge via R3 and R5 causing the voltage at R4/R5 to rise again. The result is a falling frequency until the oscillator switches off, returning the circuit to its original condition. As well as reducing the current drawn by the circuit to zero, this mimics the action of a conventional whistling kettle, where the frequency rises as more steam is produced and then falls when it is taken off the boil. 

The circuit is powered directly by the mains using a ‘lossless’ capacitive mains dropper, C6, and zener a diode, D2, to provide a nominal 8 V dc supply for the circuit.  A 1-inch reed switch used in the prototype required about 9 turns of wire to operate with a 2-kW kettle element. Larger switches or lower current may require more turns. In general, the more turns you can fit on the reed switch, the better, but do remember that the wire has to be thick enough to carry the current. It is strongly recommended to test the circuit using a 9-volt battery instead of the mains-derived supply voltage shown in the circuit diagram. A magnet may be used to operate S1 and so simulate the switching of the kettle. 

Warning. This circuit is connected directly to the 230-V mains and none of the components must be touched when the circuit is in use. The circuit must be housed in an approved ABS case and carry the earth connection to the load as indicated. Connections and solder joints to components with a voltage greater than 200 volts across them (ac or dc) must have an insulating clearance of least 6 mm. An X2 class capacitor must be used in position C6.

Author :Bart Trepak

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Simple Digital Step-Km Counter Circuit Project

Digital Step-Km Counter Circuit Diagram. This circuit measures the distance covered during a walk. Hardware is located in a small box slipped in pants' pocket and the display is conceived in the following manner: the leftmost display D2 (the most significant digit) shows 0 to 9 Km. and its dot is always on to separate Km. from hm. The rightmost display D1 (the least significant digit) shows hundreds meters and its dot illuminates after every 50 meters of walking. A beeper (excusable), signals each count unit, occurring every two steps. A normal step was calculated to span around 78 centimeters, thus the LED signaling 50 meters illuminates after 64 steps (or 32 operations of the mercury switch), the display indicates 100 meters after 128 steps and so on.

For low battery consumption the display illuminates only on request, pushing on P2. Accidental reset of the counters is avoided because to reset the circuit both push buttons must be operated together. Obviously, this is not a precision meter, but its approximation degree was found good for this kind of device. In any case, the most critical thing to do is the correct placement of the mercury switch inside of the box and the setting of its sloping degree.

Digital Step-Km Counter Circuit diagram:

Digital Step-Km Counter Circuit Diagram

Parts:
R1 = 22K 1/4W Resistor
R2 = 2.2M 1/4W Resistor
R3 = 22K 1/4W Resistor
R4 = 1M 1/4W Resistor
R5 = 4.7K 1/4W Resistor
R6 = 47R 1/4W Resistor
R7 = 4.7K 1/4W Resistor
R8 = 4.7K 1/4W Resistor
R9 = 1K 1/4W Resistor
C1 = 47nF 63V Polyester Capacitor
C2 = 100nF 63V Polyester Capacitor
C3 = 10nF 63V Polyester Capacitor
C4 = 10µF 25V Electrolytic Capacitor
D1 = Common-cathode 7-segment LED mini-display (Hundreds meters)
D2 = Common-cathode 7-segment LED mini-display (Kilometers)
Q1 = BC327 45V 800mA PNP Transistors
Q2 = BC327 45V 800mA PNP Transistors
P1 = SPST Pushbutton (Reset)
P2 = SPST Pushbutton (Display)
IC1 = 4093 Quad 2 input Schmitt NAND Gate IC
IC2 = 4024 7 stage ripple counter IC
IC3 = 4026 Decade counter with decoded 7-segment display outputs IC
IC4 = 4026 Decade counter with decoded 7-segment display outputs IC
SW1 = SPST Mercury Switch, called also Tilt Switch
SW2 = SPST Slider Switch (Sound on-off)
SW3 = SPST Slider Switch (Power on-off)
BZ = Piezo sounder
B1 = 3V Battery (2 AA 1.5V Cells in series)

Circuit operation:

IC 1A & IC 1B form a monostable multi vibrator providing some degree of freedom from excessive bouncing of the mercury switch. Therefore a clean square pulse enters IC2 that divides by 64. Q2 drives the LED dot-segment of D1 every 32 pulses counted by IC2. Either IC3 & IC4 divide by 10 and drive the displays. P1 resets the counters and P2 enables the displays. IC1C generates an audio frequency square wave that is enabled for a short time at each monostable count. Q1 drives the piezo sounder and SW2 allows disabling the beep.

Notes:

• Experiment with placement and sloping degree of mercury switch inside the box: this is very critical.
• Try to obtain a pulse every two walking steps. Listening to the beeper is extremely useful during setup.
• Trim R6 value to change beeper sound power.
• Push P1 and P2 to reset.
• This circuit is primarily intended for walking purposes. For jogging, further great care must be used with mercury switch placement to avoid undesired counts.
• When the display is disabled current consumption is negligible, therefore SW3 can be omitted.

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Digital Cranial Electrotherapy Stimulator Circuit Project

This is a simple Digital Cranial Electrotherapy Stimulator Circuit Project. Current generated flows through clips placed on the earlobes Output current adjustable from 80 to 600 micro Amperes. Owing to the recent launching in Europe of Cranial Electrotherapy Stimulation (CES) portable sets, we have been "Electronically Stimulated" in designing a similar circuit for the sake of hobbyists. CES is the most popular technique for electrically boosting brain power, and has long been prescribed by doctors, mainly in the USA, for therapeutic reasons, including the treatment of anxiety, depression, insomnia, and chemical dependency. CES units generate an adjustable current (80 to 600 microAmperes) that flows through clips placed on the earlobes. 

The waveform of this device is a 400 milliseconds positive pulse followed by a negative one of the same duration, then a pause of 1.2 seconds. The main frequency is 0.5 Hz, i.e. a double pulse every 2 seconds. Some people report that this kind of minute specialized electrical impulses contributes to achieve a relaxed state that leaves the mind alert. Obviously we can't claim or prove any therapeutic effectiveness for this device, but if you are interested in trying it, the circuit is so cheap and so simple to build that an attempt can be made with quite no harm.

Parts:
R1___________1M5 1/4W Resistor
R2___________15K 1/4W Resistor
R3___________100K Linear Potentiometer
R4___________2K2 1/4W Resistor
C1___________330nF 63V Polyester Capacitor
C2___________100µF 25V Electrolytic Capacitor
D1___________3mm. Red LED
IC1___________7555 or TS555CN CMos Timer IC
IC2___________4017 Decade counter with 10 decoded outputs IC
SW1__________SPST Slider Switch
B1____________9V PP3 Battery Clip for PP3 Battery
Two Earclips with wires (see notes)

Circuit operation:

IC1 forms a narrow pulse, 2.5Hz oscillator feeding IC2. This chip generates the various timings for the output pulses. Output is taken at pins 2 & 3 to easily obtain negative going pulses also. Current output is limited to 600µA by R2 and can be regulated from 80 to 600µA by means of R3. The LED flashes every 2 seconds signaling proper operation and can also be used for setting purposes. It can be omitted together with R4, greatly increasing battery life.

Notes:

• In order to obtain a more precise frequency setting take R1=1M2 and add a 500K trimmer in series with it.
• In this case use a frequency meter to read 2.5Hz at pin 3 of IC1, or an oscilloscope to read 400msec pulses at pins 2, 3 or 10, adjusting the added trimmer.
• A simpler setting can be made adjusting the trimmer to count exactly a LED flash every 2 seconds.
• Earclips can be made with little plastic clips and cementing the end of the wire in a position suited to make good contact with earlobes.
• Ultra-simple earclips can be made using a thin copper foil with rounded corners 4 cm. long and 1.5 cm. wide, soldering the wire end in the center, and then folding the foil in two parts holding the earlobes.
• To ensure a better current transfer, this kind of devices usually has felt pads moistened with a conducting solution interposed between clips and skin.
• Commercial sets have frequently a built-in timer. Timing sessions last usually 20 minutes to 1 hour. For this purpose you can use the Timed Beeper the Bedside Lamp Timer or the Jogging Timer circuits available on this website, adjusting the timing components in order to suit your needs.

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Electronic Animation to Explain Complex Principles

Simple animation to explain complex principles - Electronics

1, aircraft radial engine



2, oval Regulation



3, sewing machines



4, Malta Cross movement - second hand movement used to control the clock



5, auto change file mechanism



6, auto constant velocity universal joint

6.gif

7, gun ammunition loading system



8 rotary engine - an internal combustion engine, the heat rather than the piston movement into rotary movement





# Via World Of Technology. HowStuffWorks see from the attached three car engine diagram:

1, inline engine - it's cylinders lined up side by side



2, V-type engine - cylinder arranged at an angle of two plane

3, boxer engine - cylinder engine arranged in two planes relative

By Geethalakshmi,

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