Specs for the :  At 3VDC we measured 150mA @ 120 RPM no-load, and 1.1 Amps when stalled.   At 4.5VDC we measured 155mA @ 185 RPM no-load, and 1.2 Amps when stalled   At 6VDC we measured 160mA @ 250 RPM no-load, and 1.5 Amps when stalled.  I was looking around for some motor drivers to drive 4 of those motors. I'm planning to go with the  (which I already have 1 of, so I would only need 1 more) or  (which I would need 2 of). I'm sure that the DRV8833 is definitely capable of driving those motors, but I'm not sure about the L293D (which would be preferable considering its price and that I need only one more) According to the specifications of the L293D motor driver on the website, these seem to be able to drive motors below 600mA, which I believe should be fine for the motors, however, it lists that it can handle a peak of only 1.2A, but the motors states that it can go up to 1.5A of current when stalled at 6VDC (not sure what stalled current means, exactly, but it's bugging me a bit). Would the L293D be just fine for this or would, say, the DRV8833 be a bit more suitable for the motors? Would appreciate any help, thanks!
16871
This question is about the following three integrated H-bridge drivers: -    or L293D (D = protection diodes added)  (protection diodes included)  (no protection diodes)   Time after time the same question keeps coming up - someone is using one of these devices (on a low voltage, usually around 6V or less) and they are just not performing adequately. The reasons are listed further below but my question is this: -  What H-bridge drivers are preferred when controlling a low-voltage motor?   Information  The L293 and the SN754410 are nearly identical and crucially, if you try and control a 1 amp load, you are faced with dismal performance: -    The tables tell you (typical conditions) that the upper transistor drops (loses) about 1.4 volts when driving a 1A load and, the lower transistor drops (loses) about 1.2 volts when driving a 1A load. The upshot is that if you have a 6V, 1A motor and 6V battery, don't expect to see more than 3.4 volts across the motor: -  \$V_{OUT} = 6V - (1.4V + 1.2V) = 3.4V\$  Worst case scenario is you might only see 2.4 volts across it.  What about the L298? It's got a nice big heat-sink whereas the L293 and SN754410 are regular-looking chips. Here's what the volt drop (losses) look like: -    It's the same story - for a 1A load, you can expect to lose up to 3.2 volts and, what you thought might be 6V across your motor, is at best 4.2 volts and at worst only 2.8 volts.  Clearly none of the devices listed are suitable for low voltage applications where the motor might be expected to draw in excess of 0.5 amps.
56962
1.) I have a brushless motor with testing data at 12V. I want to know if I increase the voltage supply, will this increase the torque?   In my research I keep seeing "current controls torque, and voltage controls speed." But that doesn't seem quite right. Let's say I have a theoretical electrically powered unicycle that is weighted. With a 5V source and 2A, the motor can't move the unicycle. But now I increase the voltage to 10V, and I believe current will also increase by x2 if resistance is constant (V = IR). So now the torque increases and the unicycle can move itself. It that a reasonable sequence of events? Can I say that increasing voltage increases torque?   2.) A similar question: if P = VI = tau*omega, then P/omega = tau, so:  2*(P/omega) = 2*tau, which means increasing power will increase torque, correct? And since P = VI, increasing V will increase P, which will in turn increase torque. Is this accurate at all?
65853
In the below mentioned circuit which is used for automotive EMR braking. We are facing freewheeling diode burn out (FR607 is currently being used).     We are still clueless about the cause. But as per design this is a 6 A rated diode with surge value of 300 A which according to my design team is well enough. But we suspect that this ampere rated diode is not OK.  We need to find the maximum freeweeling current in this circuit. How to calculate this current value. The coil resistance is 0.8 amps. Load of the circuit is 30 amps and the supply is a 24 V DC battery source 200 Ah.
75689
I am attaching a motor to an ATmega32 chip. I want to build an H-bridge but before doing that, I want to control the motor using the chip. I bought few NPN Transistors from RadioShack. I have 5V running though the breadboard. I attached Vcc to the Collector, Base to the Pin, and Emitter to the motor. And other wire of motor is hooked up to Ground. Unfortunately, the power coming out of the transistor is too low, the motor is barely moving (As opposed to when I hook up my motor straight to 5V). What is wrong? Do I need a different transistor or is my setup wrong? If it is the transistor, can you please recommend the right one, I am not too good at those.
91421
I want to know the function of the three 1Mohm resistor between the HVDC+ and HDVC-, they are R4 R14 and R17 in the below circuit, thanks for your attention and time!
109513
Based on my , since there supposed to be zero voltage (V=IR) drop across a 0&nbsp;Ω resistor, how do we select the  of such a component?  For example, let's say I were to connect a zero-ohm resistor in between 5&nbsp;V power source and a load (circuit variant) which take current ranges from 20-200&nbsp;mA. What is the power rating of the 0&nbsp;Ω resistor I should select?
83921
I've been trying to get this simple FM transmitter to work over the past few days and I could use some help in a few areas.      First iteration was on a breadboard with all parts included.  The exception being I didn't have a 0.1uH coil handy but I had another coil rated at 0.7uH (using my LCR meter).  I also didn't have a C4 value of 4.7pF but I had a 10pF value.  I figured I could just tune it later.  I hooked a scope up to it and got no oscillation.  I tried connecting the probe to the gate and the collector separately and together.  Still no oscillation.  Second iteration.  I removed the audio component of the circuit.  Essentially everything to the left of C2.  I had gotten that working no problem anyway so I figured I would concentrate on the oscillator.  This time I tried different values for the inductor ranging from 20uH to 1mH and different fixed values for the variable cap (10pf, 20pf, 30pf).  These were all ceramic caps. No love.  Third iteration. I tested the transistor to make sure that wasn't the issue.  Seems fine.  PN2222A variety. (Also tried 2N3904 and BC547). I then modeled this up on a piece of perf board.  I even found a SMD inductor of 0.1uH so now I thought I would be good.  Tested all the pieces on the meter before installation. Still nothing. I'm not seeing anything on the spectrum analyzer either.  Questions:   Do you think my benchtop power supply is causing a problem?  All the various versions of this type of FM transmitter circuit on YouTube and the Internet all seem to use a battery.  Any chance the 60Hz main power is messing with things?  I've put .1uF and higher caps on the power rails. I have a 200Mhz SIGLENT SDS1202X-E scope.  I've built and tested other oscillators up to a few MHz before with no issues.  Any thoughts on that being the issue?  I would expect to see something on the scope right? Any chance the probe is dampening the oscillations?     I know there are a lot better FM transmitter circuits out there I was just experimenting with this (and others like it) and couldn't get any to work.
78706
I'm new to electrical engineering, and probably asking the wrong question. Not sure how else to phrase it.  For the question, I'm going to use an example layout of simply a 9v battery attached to a toy DC motor.  From my understanding of my , the voltage coming from the battery through the motor will be around 9v. The current will be from 0amps to however much the battery can supply without frying. What decides how much current goes through the motor?
41588
So I found this 9V 1A AC power supply laying around and decided to make a DC source.  I rectified and added a capacitor to make things a bit even. After adding a capacitor my voltage boosted from 9V to 14V. Can somebody explain why this happened for me? (maybe this has something to do with frequency?) According to theoretical graph I should get aprox the same voltage even after adding the capacitor. And voltage varies depending on how much capacity the capacitor has (aprox. from 12-16V). Maybe there's some sort of equation to determine the actual output voltage depending on caps? It would be great to get 12V out of this thing.   P.S.: Personally I find this boost weird because this circuit doesn't have any switches and coils to boost the voltage, so I need an explanation, thank you in advance!
123253
I'm trying to use an  and an Arduino UNO R3 to drive a bipolar stepper motor.   To simplify things, I'm just trying to get a 12v output from either output-1 or output-2 of the l298 (then I can write up the 2nd h-bridge in the l298 the same way and be able to drive both motor coils).  I'm only getting ~130mv from output-1 and 140mv from output-2 (measured between the power supply ground wire and output-1/output-2). The motor is a 12v motor, but I've been able to drive it with an l293 which provides only 6v.  I am getting 5v on the logic supply voltage pin and ~4v on the enable pin (using analogWrite(3, 200) - tried with the enable pin connected to either the analog pin 3 or the digital pin 3 (labeled pwm)).  I have measured supply voltage to be 11.85v (12v power supply).  I have followed the wiring/code from  and  (using same arduino code, but they got it to work, and I can't).  I have tried connecting the Current Sensing A pin to the power supply ground as suggested on the 2nd web page.  I have double checked that I have wired it up the same way. I've tried everything on both web pages and the few other pages I can find about building a circuit with an l298n and an arduino and I'm out of ideas about what to try next.  Is there anything I can do?  Here's a picture of what I built:
96004
I'm hooking up a small DC motor to an arduino using an NPN transistor using the following diagrams I found online:       The circuit works, and I'm successfully able to make the motor run.  Now, I'm seeking to understand why it works the way it does.  In particular, I'd like to understand:     Why are the diode and capacitor hooked up in parallel to the motor?  What role do they serve here?   Why is a resistor needed between the transistor and the digital PWM pin on the arduino?  Would it be safe to run the circuit without it?
91558
I have a circuit which uses an ATtiny85 output to a transistor (S9013), which will trigger a relay that controls a motor.  The reason for the transistor to relay is because I do not have a transistor that can take the current of the motor, so I am isolating it with a relay.  While I can purchase all these, it will take time to ship.  Here is the circuit:   SCHEMATIC NOT UPDATED, I HAVE A DIODE GOING ACROSS THE MOTOR, AND A 100uF CAPACITOR GOING ACROSS THE VCC AND GND TO SMOOTH OUT THE VOLTAGE (have also tried 100nF).  Everything works if I don't connect the motor OR if I isolate the motor with its own power source.  The issue now is that when the motor is switched on, there is a massive voltage drop and the ATtiny85 will reset. Here is a waveform of the motor trying to turn on three times:    Is there a way to prevent this drop or at least reduce it to a point where the ATtiny85 won't reset? I'm thinking wire up a simple voltage regulator but not sure if the added complexity will introduce other issues. I also know I can go out and buy a motor or voltage regulators but let's avoid that option.  EDIT: so as per the answer, a diode (cathode at +ve, anode at VCC) was added between +ve and VCC, assuming that there is a capacitor connected in parallel with the ATtiny85 (+ve end at VCC, -ve end at GND). Theory is that the cap gets charged while the motor is off to VCC. When the motor turns on, it's going to drop that voltage down to below VCC and the diode is going to be reverse-biased and prevent any conflict from the supply to going into the ATtiny85. The capacitor can now freely discharge into the ATtiny85 without the supply affecting it (without the diode, supply will average capacitor down faster than if it would just discharge alone). For reference, the bulk capacitance value I used was 100uF.
10727
What would be the least expensive way to boost a DC voltage?   The aim is to convert 1.2&nbsp;V/1.5&nbsp;V (from an AA/AAA cell) to 3.3&nbsp;V to power a small 8-bit microprocessor, like Atmel ATtiny45 or ATtiny2313, and also (if possible) 6&nbsp;V to power a buzzer.  Also, what would be the maximum current one could draw safely from an alkaline battery, after boosting it to 3.3&nbsp;V/6&nbsp;V?  Finally, how I could compute the duration for which the alkaline battery would last, given a certain consumption?
38098
I'm trying to use an  linear voltage regulator to convert to 3.3v (input voltage will be 9 or 5 volts; not yet decided). The datasheet suggests using 10uF tantalum capacitors on the input and output. While I could just go with the suggestion, I find most of the tantalum capacitors that are available are considerably more expensive than other capacitors, and in a SMT form factor (I'd prefer through-hole). I'm thinking of using aluminum or ceramic caps instead.   This excerpt from the datasheet specifies what ESR ranges are acceptable:     8.2.2.1.3 Output Capacitor   The output capacitor is critical in maintaining regulator stability, and must meet the required conditions for both   minimum amount of capacitance and equivalent series resistance (ESR). The minimum output capacitance   required by the LM1117 is 10 µF, if a tantalum capacitor is used. Any increase of the output capacitance will   merely improve the loop stability and transient response. The ESR of the output capacitor should range between   0.3 Ω to 22 Ω. In the case of the adjustable regulator, when the CADJ is used, a larger output capacitance (22-µF   tantalum) is required.   As I understand it, ceramic caps have a very low ESR. Could I just add a 0.3 Ω to 22 Ω resistor in series with a ceramic capacitor? I've read what ESR is and isn't, and I don't understand it one bit, so right now it's just a range of numbers I'm trying to match. However, ceramic caps tend to have smaller capacitance, so it might not be as easy to get 10uF ceramic caps.   If I recall correctly, aluminum caps have a much higher ESR (though exactly what "higher" means I'm not sure). Additionally, it can be difficult to get a datasheet for a capacitor simply because they're such common components (I'm in China and purchasing online, but don't read Chinese). So I'm not sure how to make sure I'm within the ESR range specified.  Finally I should note that I don't have any of these components yet, but I'll probably get an assortment of capacitors when I do order.  So my question: What capacitors can be used in this situation, and with what value resistors (if any)? Note that I'm interested in the theory, not just this single situation, but not being experienced with capacitors some specific examples could be helpful.  Related:
81205
I have disassembled 20 broken hard disks and taken out the motors, thinking they might be useful. However, they didn't work using DC current, because they required some kind of control circuit. Now I have a project (electrolysis) that might require to use those motors as generators. I want to know what kind of current these generate (DC or AC)? They were able to power an LED but as LEDs are diodes, I couldn't tell whether that motor generated AC.
16505
My laptop's cable broke and sadly it seems like I need to buy a new power supply.  What I wonder is, I've found that universal power supplies are much cheaper than the official HP ones. Are they really worth it?  Another question: the original supply has these specs: 65W, 18.5V, 3.5A. However the universal supplies are more powerful (90W, 100W) and come in integer voltages (17V, 18V, 19V, etc). Are they compatible? Should I set them to 18V or 19V?
95935
I have ordered a Dual H-Bridge 12A continuous (30A peak) Polulu motor driver shield for my upcoming (first time ever, a 1.2m long tank made of wood) robot project.   I was thinking about how to supply the power to all the components in the circuit without wasting much power, but the only thing I can come up with is this simple voltage divider connected in parallel to the motor drive:    Knowing the Arduino can handle max 5V I did make sure to make it a bit lower.  But my wonders go to the fact that I am suspicious that connecting the motor driver and Arduino to the same power source isn't a great idea? Or am I paranoid?  And what about power waste by the voltage divider, how can I reduce/minimize it? Make the resistors smaller? (15/10 ohm - but more error and higher current)  Is there a formula to find the most effective R1 and R2?  Do I have to worry about current spikes?  Any other things I could miss in this simple-yet-suspicious circuit?  Also, if I wanted to simulate any possible scenario, which components should I choose in the circuit to keep it as simple as possible (for simulating in Multisim 13)?