New answers tagged

0

Forget the 555, use a counter instead. Here's a project that does exactly that, as a complete design: https://www.electronics-lab.com/project/long-duration-timer/ Or use a microcontroller. ATTiny would be ideal for this - it has an internal oscillator so all you need is the switch to trigger it and the driver transistor for the relay (hint: use an N-FET and ...


0

The idea of supplying a fixed DC voltage to the field from a separate power supply seems like a good plan. The original machine very likely had at least the rated current marked on it. The motor seems to have the voltage marked on it and perhaps also the power. There may have also been a diagram of the internal control circuits on the back of the machine. ...


-3

In this circuit capacitys it act as filters to filter the ripples of ac to allow DC only to move to motors because this motors the allow 12v of DC only to operate. And we are known that capacity is a device that can use to storage the charges


-3

In this circuit capacity it act as filt to filt the ripples of ac to allow DC only to move. And we are known that capacity is a device that can use to storage the charges in a circuit


2

Yes and no. simulate this circuit – Schematic created using CircuitLab Figure 1. The wiring circuit. The problem is that motors don't behave like resistors. The more load you put on the motor the lower its resistance will become and the more current it will try to draw. If you got the right lamp it could protect the motor enough but when the motor ...


26

Generally a 0.01~0.1uF capacitor is wired across brushed DC motors to reduce radio frequency EMI caused by arcing between the brushes and commutator. Sometimes two capacitors are wired in series, with the center connection going to the case to 'ground' it at RF frequencies. For best effect the capacitor(s) should be placed on or inside the motor. In this ...


1

Your understanding (higher flux = higher torque = lower speed) is not wrong, but it's based around a motor whose construction is reasonably close to the ideal, which is difficult to achieve with simple hand construction as seen in that video. Now consider a motor with much less ideal construction, where bearings and brushes have significant friction, and ...


1

How does magnetic flux affects the speed of a DC motor It's all about how does current get to flow in the rotor... Scenario 1 You have high flux and the rotor is spinning constantly at a moderate speed on no load. The rate of change of flux (\$\frac{d\Phi}{dt}\$) seen by the rotor is such that \$\frac{d\Phi}{dt}\$ induces an equal and opposite voltage in ...


11

DC motors use brushes on the commutators. These spark due to inductance of the coils as they switch from segment to segment. Figure 1. Communtators and brushes. Image source: eReplacmentParts. The capacitor shunts (or "absorbs") the high frequency spikes from the commutation and prevents damage to the driver chips. A further factor not clear from the ...


7

Your question is probably only answerable through context; you're right, instead of C2 and C6, everyone would expect flyback diodes, forming a ground path for voltage spikes that happen upon switching off an output. Maybe these capacitors are supposed to fulfill the same role? Generally, you'd avoid having capacitance here – it's hard enough on the output ...


4

Maybe the motor overloaded and burned out the transistor.


2

As mentioned above by @Marko Buršič you can just connect the motor to the supply to check if it is working. If this is the case then I would try driving the circuit off another GPIO pin to see if that works. The motor is a reactive load which is why there is a diode (IN4148) to protect the pi against back EMF. If the diode has failed or the wiring is faulty ...


1

There is no co-relation between a battery's remaining capacity and it's open-circuit voltage. The discharged battery's no load voltage could be above 12 V but its internal resistance would also be high. Without the required starting current, the motor would remain stationary and present itself as a dead short across the battery terminals. The battery ...


0

12 Ah specifies how much charge is stored in each battery (1 Ah is 3600 Coulombs). It reveals how long the battery can supply a given current. However, the batteries will also have a maximum power rating (in Watts or VA) that reveals the maximum rate at which it can deliver the charge. If the power rating were unbounded, then the battery could deliver all ...


0

how can I increase speed and decrease torque keeping watts same. Please explain for dc and bldc motor. Brushed or brushless DC makes no difference, the principle is the same. When the rotor/armature is spinning the motor acts as a generator, producing a voltage proportional to rpm (Faraday's Law). This voltage opposes the supply voltage. The difference ...


0

The speed of a d.c. motor is given by $$ N = \frac { V - I_a.R_a}{kφ} $$ where 'V' is the applied voltage, 'Ia' the armature current, 'Ra' the armature resistance, 'k' a constant based on the number of poles, the number of conductors and number of parallel paths in the armature and 'φ' the flux per pole. That speed could be either increased or decreased ...


6

A 5 ohm resistor will try to draw a current of 4.8 amperes from a 24 volt power supply. You say you measure currents of 280 mA and 400 mA with 2 different supplies. Clearly neither supply is providing 24 volts. If you want to test your supplies at the same current level as your motor, you need a much larger resistor (24/0.18 = 133 ohms). Also, have your ...


0

Well, It turned out that i haven't connected enough ground wires. After connecting almost every ground wire to my circuit, it started working!


1

When BLDC motors off, do they affect my normal riding... Yes. The attraction between the magnets and the steel core fo the windings will cause "reluctance torque" that will be like a small amount of braking. If the coils are connected together through the ESC, there can be generator action that could be used to charge the batteries, but that would add to ...


2

You must make sure that the motors do not drain your capacitor. Try adding a (Schottky) diode before the LDO and put the capacitor after the diode and before the LDO: simulate this circuit – Schematic created using CircuitLab


1

First some back ground information: This is the schematic of your L298 controller board. This is the datasheet of the L298. This is the documentation of the Raspberry Pi GPIO pins. From the Raspberry Pi GPIO documentation: Connection of a GPIO to a voltage higher than 3.3V will likely destroy the GPIO block within the SoC. From the datasheet of the ...


1

As Oldfart mentioned, the datasheet reveals that the +5v is not optional; it is the logic supply of the L298 chip. It is very likely that your raspberry pi was sinking/sourcing way more current than it could handle. The datasheet does not define the behavior of the chip when the logic supply is not connected but I think it's safe to assume that this caused ...


0

If you want to have a reversible convertor, imagine a buck or boost topology (no matter which one of them, one is a reverse to the another). Generally, it consist of two switches and if you don't want the reverse capability, one of the switches is a diode so it drives itself and you have only to drive the other one. If you drive both switches in anti-phase, ...


0

Can I simply connect a Zener diode in reverse in parallel with the boost converter, which breaks down at some voltage above 36V, e.g. 37V? You can do that, but it won't have any effect unless the motor is being mechanically driven at higher than normal speed. To brake the motor you can switch a resistor across it. The lower the resistance the more ...


1

C3 , at 22uf, is way way way too small. And you have no ground plane. Get copper tape, place that on backside of your PCB, insulated in some way, and solder the copper tape to a number of GND nodes.


0

Congratulations on asking a good question that should have been covered by the instructor. The battery will be damaged or destroyed if left on charge when the battery is fully charged. A 1S LiIon cell must NEVER be charged to above 4.2V. It MUST NOT be floated at 4.2V It can be floated at 4.1V or less. 4.1V max still gives most of capacity, 4.0V is lower ...


2

Just a few thoughts to help you on your way: Bicycle speedometers use a magnet on the front wheel to trigger a magnet-sensing switch (a "reed" switch) on the fork. By measuring the time between pulses and using the wheel circumference you can calculate the speed. You can use the same sensor arrangement on the pedals if you want to know the "cadence" (number ...


3

My initial thought was to use an DC motor as generator to convert speed to an voltage we can read(with an power resistor to dissipate the power produced) Yes, go with that. If the generator is large enough, and the power resistor is large enough, they can dissipate all the power produced and there is no need for a second motor as a load. Filament lamps ...


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