Showing posts with label for. Show all posts
Showing posts with label for. Show all posts
Thursday, April 11, 2013
How to Lights Control for Model Cars
The author gave his partner a radio controlled (RC) model car as a gif t. She found it a lot of fun, but thought that adding realistic lights would be a definite improvement. So the author went back to his shed, plugged in his soldering iron, and set to work equipping the car with realistic indicators, headlights, tail lights and brake lights.
Lights Control for Model Cars Circuit Diagram
The basic idea was to tap into the signal from the radio control receiver and, with a bit of help from a microcontroller, simulate indicators using flashing yellow LEDs and brake lights using red LEDs. Further red LEDs are used for the tail lights, and white LEDs for the headlights. Connectors JP4 and JP5 (channel 0) are wired in parallel, as are JP6 and JP7 (channel 1), allowing the circuit to be inserted into the servo control cables for the steering and drive motor respectively. The ATtiny45 micro-controller takes power from the radio receiver via diode D1. T1 and T2 buffer the servo signals to protect IC1’s inputs from damage.
IC1 analyses the PWM servo signals and gen-erates suitable outputs to switch the LEDs via the driver transistors. T3 drives the two left indicators (yellow), T4 the two right indica-tors, and T5 the brake LEDs (red). The red tail lights (JP2-8 and JP2-8) and the white head-lights (JP2-9 and JP2-10) are lit continuously. The brake lights are driven with a full 20 mA, so that they are noticeably brighter than the tail lights, which only receive 5 mA. If you wish to combine the functions of tail light and brake light, saving t wo red LEDs, sim-ply connect pin 10 of JP2 to pin 14 and pin 12 to pin 16. Then connect the two combined brake/tail LEDs either at JP2-5 and JP2-6 or at JP2-7 and JP2-8.
JP3 is provided to allow the use of a separate lighting supply. This can either be connected to an additional four-cell battery pack or to the main supply for the drive motor. The val-ues given for resistors R8 to R17 are suitable for use with a 4.8 V supply. JP2 can take the form of a 2x10 header.
As usual the sof t ware is available as a free download from the Elektor web pages accom-panying this article[1], and ready-programmed microcontrollers are also available. The microcontroller must be taught what servo signals correspond to left and right turns, and to full throttle and full braking. First connect the fin-ished circuit to the radio control electronics in the car, making sure everything is switched of f. Fit jumper JP1 to enable configuration mode, switch on the radio control transmit-ter, set all proportional controls to their cen-tre positions, and then switch on the receiver. The indicator LEDs should first flash on both sides. Then the car will indicate left for 3 s: during this time quickly turn the steering on the radio control transmitter fully to the left and the throt tle to full reverse (maximum braking).
Hold the controls in this position until the car starts to indicate right. Then set the controls to their opposite extremes and hold them there until both sides flash again. Now, if the car has an internal combustion engine (and so cannot go in reverse), keep the throttle control on full; if the car has an electric motor, set the throttle to full reverse. Hold this position while both sides are flashing. Configuration is now complete and JP1 can be removed. If you make a mistake during the configuration process, start again from the beginning. link
JP3 is provided to allow the use of a separate lighting supply. This can either be connected to an additional four-cell battery pack or to the main supply for the drive motor. The val-ues given for resistors R8 to R17 are suitable for use with a 4.8 V supply. JP2 can take the form of a 2x10 header.
As usual the sof t ware is available as a free download from the Elektor web pages accom-panying this article[1], and ready-programmed microcontrollers are also available. The microcontroller must be taught what servo signals correspond to left and right turns, and to full throttle and full braking. First connect the fin-ished circuit to the radio control electronics in the car, making sure everything is switched of f. Fit jumper JP1 to enable configuration mode, switch on the radio control transmit-ter, set all proportional controls to their cen-tre positions, and then switch on the receiver. The indicator LEDs should first flash on both sides. Then the car will indicate left for 3 s: during this time quickly turn the steering on the radio control transmitter fully to the left and the throt tle to full reverse (maximum braking).
Hold the controls in this position until the car starts to indicate right. Then set the controls to their opposite extremes and hold them there until both sides flash again. Now, if the car has an internal combustion engine (and so cannot go in reverse), keep the throttle control on full; if the car has an electric motor, set the throttle to full reverse. Hold this position while both sides are flashing. Configuration is now complete and JP1 can be removed. If you make a mistake during the configuration process, start again from the beginning. link
Electrical Isolation For I2C Bus
When the SDA (Serial DAta) lines on both the left and right lines are 1, the circuit is quiescent and optoisolators IC1 and IC2 are not actuated. When the SDA line at the left becomes 0, current flows through the LED in IC1 via R2. The SDA line at the right is then pulled low via D2 and IC1. Optoisolator IC2 does not transfer this 0 to the left, because the polarity of the LED in IC2 is the wrong way around for this level. This arrangement prevents the circuit holding itself in the 0 state for ever. As is seen, the circuit is symmetrical. So, when the SDA line at the right is 0, this is transferred to the left. The lower part of the diagram, intended for the SCL (Serial CLock) line, is identical to the upper part.
Resistors R1, R4, R5, and R8, are the usual 3.3 kΩ pull-up resistors that are obligatory in each I2C line. If these resistors are already present elsewhere in the system, they may be omitted here. The current drawn by the circuit is slightly larger than usual since the pull-up resistors are shunted by the LEDs in the optoisolators and their series resistors. Nevertheless, it remains within the norms laid down in the I2C specification.
Continue reading...
Resistors R1, R4, R5, and R8, are the usual 3.3 kΩ pull-up resistors that are obligatory in each I2C line. If these resistors are already present elsewhere in the system, they may be omitted here. The current drawn by the circuit is slightly larger than usual since the pull-up resistors are shunted by the LEDs in the optoisolators and their series resistors. Nevertheless, it remains within the norms laid down in the I2C specification.Tuesday, April 9, 2013
IC LA78040 schematic for vertical deflection
Synchronization circuit to make the signals useful in the process of scanning of the transmitter and sent to the Vertical and Horizontal. To be able to produce images on the picture tube phosphor surface is the same as what was sent, then the necessary adjustments to correct with ualsan which has decomposed on the sender and receiver on the review must be made again, and this is called synchronization.
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On TV transmitter switching pulses that have made the same frequency as in the reviewing, and by using the switching pulse is then mulapenguilasan point getter on the tube and picture tube can be adjusted simultaneously.
At the transmitter, each end of the line reviews one pulse is emitted horizontally, and also at each end of the line vertical review (this is called a field review), another pulse is emitted. At the receiver using switching pulses had the time of the beginning (start) review can be arranged horizontally and vertically. Switching pulses are called the horizontal synchronizing signal and vertical synchronization.Vertical SynchronizationA. Vertical in the tv series has the following functionsa) bend / open beams of light (information) to the vertical direction.b) Synchronize files from a transmitter in the form of images with short time.
Sunday, April 7, 2013
Rear Light After Glow For Bicycles
This article is of interest only to readers whose bicycle lights are powered by a dynamo. The laws on bicycle lights in the United Kingdom are stricter than in other countries and a dynamo is, therefore, a rarity in this country. From the point of view of traffic safety it is advisable (in UK obligatory) for cyclists to have the rear lamp of their bicycle to light even when they are at standstill.
In principle, it is not very difficult to modify the existing rear light with afterglow: all this needs is a large enough energy reservoir. Since the after-glow is required for short periods of time only, a battery is not required: a large value capacitor, say, 1 F, is quite sufficient.As the diagram shows, in the present circuit, the normal rear light bulb is replaced by two series-connected bright LEDs, D2 and D3. These are clearly visible with a current of only 6 mA (compared with 50 mA of the bulb).
The current is set with series resistor R1. The LEDs are shunted by the 1 F capacitor, C1. Since the working voltage of this component is only 5.5 V, it is, in spite of its high value, physically small. An effective regulator is needed to limit the dynamo voltage adequately. Normal regulators cannot be used here, since they do not work at low voltages. Moreover, such a device would discharge the capacitor when the cycle is at standstill.
Rear Light After Glow Circuit Diagram
Fortunately, there is a low-drop type that meets the present requirements nicely: the Type LP2950CZ5.0. Of course, the dynamo output voltage needs to be rectified before it can be applied to the regulator. In the present circuit, this is effected by half-wave rectifier D1 and buffer capacitor C2. Diode D1 is a Schottky type to keep any losses low – important for this application, because the ground connection via the bicycle frame usually causes some losses as well. The value of buffer capacitor has been chosen well above requirements to ensure that C1 is charged during the negative half cycles of the dynamo voltage.
Source : http://www.ecircuitslab.com/2011/06/rear-light-after-glow-for-bicycles.html
Tuesday, April 2, 2013
Simple Automatic Switch For Audio Power Amplifier
Circuit of an automatic switch for audio power amplifier stage is presented here. The circuit uses stereo preamplifier output to detect the presence of audio to switch the audio power amplifier on only when audio is present. The circuit thus helps curtail power wastage. IC1 is used as an inverting adder. The input signals from left and right channels are combined to form a common signal for IC2, which is used as an open loop comparator. IC3 (NE556) is a dual timer. Its second section, i.e., IC3(b), is configured as monostable multivibrator. Output of IC3(b) is used to switch the power amplifier on or off through a Darlington pair formed by transistors T1 and T2. IC3(a) is used to trigger the monostable multivibrator whenever an input signal is sensed.
Circuit diagram:
Automatic Switch For Audio Power Amplifier Circuit Diagram
Under ‘no signal’ condition, pin 3 of IC2 is negative with respect to its pin 2. Hence the output of IC2 is low and as a result output of IC3(a) is high. Since there is no trigger at pin 8 of IC3(b), the output of IC3(b) will be low and the amplifier will be off. When an input singal is applied to IC1, IC2 converts the inverted sum of the input signals into a rectangular waveform by comparing it with a constant voltage which can be controlled by varying potentiometer VR1. When the output of IC2 is high, output pin 5 of IC3 goes low, thus triggering the monostable multivibrator. As soon as the audio input to IC1 stops, pin 5 of IC3 goes high and pin 1 of IC3 discharges through capacitor C3, thus resetting the monostable multivibrator.
Hence, as long as input signals are applied, the amplifier remains ‘on.’ When the input signals are removed, i.e., when signal level is zero, the amplifier switches off after the mono flip-flop delay period determined by the values of resistor R8 and capacitor C3. If no input signals are sensed within this time, the amplifier turns off—else it remains on. Power supply for the circuit can be obtained from the power supply of the amplifier. Hence, the circuit can be permanently fitted in the amplifier box itself. The main switch of the amplifier should be always kept on. Resistors R1 and R2 are used to divide single voltage supply into two equal parts.
Capacitors C1 and C2 are used as regulators and also as an AC bypass for input signals. Diode D1 is used so that loading fluctuations in power amplifier do not affect circuit regulation. Transisitor T2 acts as a high voltage switch which may be replaced by any other high voltage switching transistor satisfying amplifier current requirements. Value of resistor R10 should be modified for large current requirement. The LED glows when the amplifier is on. The circuit is very useful and relieves one from putting the amplifier on and off every time one plays a cassette or radio etc.
http://streampowers.blogspot.com/2012/06/simple-automatic-switch-for-audio-power_11.html
Tuesday, March 26, 2013
Lambda Probe Readout For Carburettor Tuning
A lambda probe (or oxygen sensor) can be found on the exhaust system of most cars running on unleaded fuel. Having reached its normal operating temperature (of about 600 degrees Celsius!) the lambda probe supplies an output voltage proportional to the amount of residual oxygen measured in the exhaust gas. This information is indicative of, among others, the air/fuel ratio supplied by the carburetor(s) and hence the combustion efficiency. In modern car (and motorcycle) engines, this information is used to (electronically) adjust engine parameters like ignition timing and fuel injection. The indicator described here is intended for permanent installation on a motorcycle of which the air/fuel ratio needed to be watched, with the obvious aim engine power tuning after fitting a different set of carburetors.
Apart from this obvious technical use the unit’s bright LEDs will no doubt attract the attention of curious motorcyclists. At the local junkyard a single-wire lambda probe may be salvaged from a wrecked car. Once a suitable nut has been found, the probe can screwed into the exhaust pipe of the motorcycle, at about 30 cm from the cylinders. Since we’re talking of welding and drilling in an expensive (chrome-plated) exhaust pipe, you may find that actually fitting the probe is best left to specialists! The starting point for the design of a suitable electronic indicator is that in the noble art of carburetor tuning an air/fuel ratio of 14.7 to 1 is generally considered ‘perfect’, the range covering 16.2 to 1 (‘lean’) to 11.7 to 1 (‘rich’).
The perfect ratio typically corresponds to a probe output voltage of 0.45 V. Referring to the circuit diagram, that is the input level at which 5 of the 10 LEDs will light, including the green one, D5. If one of the red LEDs lights, the mixture is definitely too rich. Note that in general it is better to have a mixture that is a little to rich than one that’s on the lean side, hence a yellow LED lights between the green LED and the first red one. Also note that the engine needs to be at its normal operating temperature before a meaningful indication is obtained.
Continue reading...
Apart from this obvious technical use the unit’s bright LEDs will no doubt attract the attention of curious motorcyclists. At the local junkyard a single-wire lambda probe may be salvaged from a wrecked car. Once a suitable nut has been found, the probe can screwed into the exhaust pipe of the motorcycle, at about 30 cm from the cylinders. Since we’re talking of welding and drilling in an expensive (chrome-plated) exhaust pipe, you may find that actually fitting the probe is best left to specialists! The starting point for the design of a suitable electronic indicator is that in the noble art of carburetor tuning an air/fuel ratio of 14.7 to 1 is generally considered ‘perfect’, the range covering 16.2 to 1 (‘lean’) to 11.7 to 1 (‘rich’).The perfect ratio typically corresponds to a probe output voltage of 0.45 V. Referring to the circuit diagram, that is the input level at which 5 of the 10 LEDs will light, including the green one, D5. If one of the red LEDs lights, the mixture is definitely too rich. Note that in general it is better to have a mixture that is a little to rich than one that’s on the lean side, hence a yellow LED lights between the green LED and the first red one. Also note that the engine needs to be at its normal operating temperature before a meaningful indication is obtained.
Sunday, March 24, 2013
Transformerless UPS Circuit for Computers CPU
Normally when we talk about uninterruptible power supplies we imagine large inverter units with complex features, where it imperatively needs to be a pure sine wave type. Such inverters occupy enormous spaces, require bigger batteries and are immensely expensive. A little innovative thinking shows that the above cumbersome design can be replaced by just batteries and a small circuit for implementing all the necessary actions of an efficient compact transformerless UPS circuit.
However the design also a few downsides. It is specifically intended for CPU type computers only and cannot be used for other applications.
The installations procedures are complicated and time consuming and requires expertise in the field of electronics as well as computers.
Having said these, once installed the unit will provide some very useful services for a very long perid of time. Moreover the efficiency of the system will be far better than the conventional UPS systems.
Looking at the circuit we see that its all about switching the motherboard of the CPU with a set of matched outputs from a battery source which exactly corresponds to the voltages thats obtained from the power supply of the CPU.
The circuit is made up of two ICs LM338, which are set for producing exact 3.3V and 5V outputs which are appropriately bifurcated into many outputs via diodes.
The 12V outputs are taken directly from the battery, while a minus 12V output is derived by employing an extra battery.
One battery feds the LM338 circuit while the other battery generates the required -12V output for the CPU.
The switching action is implemented by a relay when power fails.
The relay simply selects the appropriate grounds while doing the reverting actions.
As long as power is available from the mains, the relay keeps the backup ground disconnected from the CPU ground, and keeps the power supply ground connected to the CPU ground via the N/C contacts.
The relay is powered by an external AC mains power supply source, which is also used for charging the batteries. Actually it can be an automatic battery charger unit, attached to the system for the required actions.
The moment AC fails, the relay disconnects the power supply ground from the CPU and connects the back up circuit ground with the CPU ground, so that the CPU now gets the required back up from the relevant outputs of the transformerless inverter circuit.
The reverting actions is done within a few ms, providing an interruptible power during power failures or brownouts.
All the outputs shown in the circuit should be carefully soldered to the relevant wires of the power supply by slightly stripping the wire insulation and then taping them. The voltages must be thoroughly confirmed before integrating the two systems together.
Part List (get the parts from me, hitman2008@live.in)
IC1, IC2 = LM338
R1, R2 = 240 Ohms,
P1, P2 = 4K7 presets
All diodes are 6 amp rated
Relay = 24V, SPDT
Battery as shown
However the design also a few downsides. It is specifically intended for CPU type computers only and cannot be used for other applications.
The installations procedures are complicated and time consuming and requires expertise in the field of electronics as well as computers.
Having said these, once installed the unit will provide some very useful services for a very long perid of time. Moreover the efficiency of the system will be far better than the conventional UPS systems.
Looking at the circuit we see that its all about switching the motherboard of the CPU with a set of matched outputs from a battery source which exactly corresponds to the voltages thats obtained from the power supply of the CPU.
The circuit is made up of two ICs LM338, which are set for producing exact 3.3V and 5V outputs which are appropriately bifurcated into many outputs via diodes.
The 12V outputs are taken directly from the battery, while a minus 12V output is derived by employing an extra battery.
One battery feds the LM338 circuit while the other battery generates the required -12V output for the CPU.
The switching action is implemented by a relay when power fails.
The relay simply selects the appropriate grounds while doing the reverting actions.
As long as power is available from the mains, the relay keeps the backup ground disconnected from the CPU ground, and keeps the power supply ground connected to the CPU ground via the N/C contacts.
The relay is powered by an external AC mains power supply source, which is also used for charging the batteries. Actually it can be an automatic battery charger unit, attached to the system for the required actions.
The moment AC fails, the relay disconnects the power supply ground from the CPU and connects the back up circuit ground with the CPU ground, so that the CPU now gets the required back up from the relevant outputs of the transformerless inverter circuit.
The reverting actions is done within a few ms, providing an interruptible power during power failures or brownouts.
All the outputs shown in the circuit should be carefully soldered to the relevant wires of the power supply by slightly stripping the wire insulation and then taping them. The voltages must be thoroughly confirmed before integrating the two systems together.
Part List (get the parts from me, hitman2008@live.in)
IC1, IC2 = LM338
R1, R2 = 240 Ohms,
P1, P2 = 4K7 presets
All diodes are 6 amp rated
Relay = 24V, SPDT
Battery as shown
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