# Tag Info

5

It's possible, with a mosfet, but there is a better way. It's typically not good to use a mosfet to burn up power with. A more typical way is to use a hardware timer to generate a Pulse Width Modulation or PWM. A PWM is a pulse type signal where over the course of a timing cycle the power is varied by varying the size of the pulse. I use this type of ...

4

It would be best if you provided current limiting for the GPIO port. It depends on the current gain of the NPN transistor, but at minimum a 200Ω series resistor from the GPIO to the NPN needs to be used to limit the current to less than 16mA. (and also use less than a total limit of 50mA on all ports)

3

I made a small robot with 4 28ByJ-48 5V steppers, however I think the 5V is the minimum recommended voltage they will run on. By increasing the voltage to the motors from 8V to 11.5V - I noticed quite a substantial increase in torque, and I could run them at a higher RPM before they started mis-stepping. I was able to run continuously and over heating was ...

3

A MOSFET is often considered to be a variable resistor so you'd think that that indeed would make a power MOSFET suitable variable power resistor element. However, nearly all power MOSFETs are designed to be used as a switching element making them easy to switch on/off but hard to make a certain resistance value. You would need to apply a very finely ...

2

H bridges are for driving high current coils or motors. You have no current limiting R. CMOS (74HC family ) has about 50 OHms driver R so you can include this with your current limiting R. Since Iv intensity in xxxx mcd is common now , the curent can reduced to a few mA for indicators with a single Rs = 470 to 1k.

2

Here is how I drive bi-color LEDs: simulate this circuit – Schematic created using CircuitLab Use a logic family that can source or sink 20ma or whatever you need to drive the LEDs. I actually don't use inverters (that solution was closest to your circuit), but a serial to parallel shift register (like a 74xx591) to drive 4 bi-color LEDs using the 8 ...

2

Your pin frequency is far too low. This establishes the basic clock used to produce the PWM. You normally want the PWM signal to have a period close to 20 ms, which corresponds to an update rate of 50 Hz. The pulse width needs to vary between 1 and 2 ms. If you want 200 steps to cover this range (-100 to +100), the pin frequency (PIN_FREQ) needs to be \...

2

Power the entire circuit from a 12V wall adaptor with enough oomph to run the solenoid, the Pi, and everything else. Then run the Pi itself from a 5V regulator that runs off of your 12V rail.

1

To get the most benefit from this, the +5V supply should be completely isolated from the 3.3v. Also, it would be best to add a diode eg. 1N4148 inverse across the series opto+LED combination to prevent possible reverse breakdown from transients. Depending on the forward voltage of the LED you might not have much voltage left for the 200 ohm resistor so the ...

1

Here is what I have gathered here from the answers, comments, and some additional research: 1) The cable that shipped with the device should work for my purposes. However, I will need to be able to install the correct driver(s). Upon further research, I was able to figure out that the device manufacturer downloads include a Windows installer for this ...

1

Is it necessary to do the ethernet cable splicing as indicated in the above link, or should I simply be able to use the provided USB cable? If you can find drivers for the R Pi then you can use the converter. I'd start by finding out what chip is in the propriety RS485 to USB, they might have a linux driver. Is it likely that the shipped cable is ...

1

The circuit shown on the breadboard doesn't match the circuit in the link you claim to be copying. The schematic in your link shows the diode in parallel with the solenoid - your breadboard drawing shows the diode in series with the solenoid. One side of the solenoid should go to the positive supply, not to ground as shown on the breadboard. Follow the ...

1

1) your solenoid connections are both wrong, this is a low side switch with Red (V+) power applied to load.. 2) your component resistances are missing e.g. DCR of solenoid , Rce of NPN transistor ( Rce=Vsat/Isat) and hFE of transistor considering the switched current gain is more like 10% of the linear hFE. take a 12W solenoid. e.g. DCR is 12 Ohms i.e. ...

1

Solution 1: For simplicity and cost IR sensor + Arduino would be a good sensor. This solution has some cons: you would need a line of sensors, to observe whole line of goal. Also, a pair (IR light emitter and a receiver) needs to occupy left and right pole of goal (or bottom-top lines of the goal). Weakness of this system is here: When ball crosses the goal ...

1

You should research you problem more broadly rather than just asking others to do it all for you. You need to know: Voltage and power level for the solenoid Voltage tolerance and power level for the 'Pi W (which will depend largely on the connected peripherals) Assuming a 'Pi W with no attached peripherals you can expect: Voltage must not go below 4.95V ...

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