If you reverse the diode connections and add a 1kΩ resistor in the middle, this will give you a constant frequency PWM, which will be a good improvement over this circuit. The capacitor will charge through Rx + 1kΩ, and discharge through Ry + 1kOhm. The total period will be ln(2)x[Rx+Ry+2kΩ]xC which is a constant because Rx and Ry sum up to the potentiometer resistance.
Diode clamps across motor will protect the 555 to some extent & provide a coasting current to flow through the motor during the pwm switch.. "off" time duration.. especially at low speeds.
Please note that whatever the load is that is connected to the output acts as an integrator, mathematically averaging out the voltage per the percentage ON of given supply voltage (at the output.)
With juat a few additional passive components & slight circuit changes ...How about a study on this circuit behaviour.... ...1) IF the osc. chg./ dischg. circuit is taken from the jn of motor term.& mosfet drain..through a suitable ( buffered) RC filter..we may get some open loop spd.regulation. ...2) A properly selected current sense resistor in series between Source & 0V (Vsense = 1/3 Vcc= I mot.limit × R sense) R_sense watts = 4×(I mot.lim.^2× R_sense)watts. This will provide some extent of current limit protection... Here the osc.cap is returned to 0 V through the R_current sense res.
Excelent video. Even though I know this circuit, and have built it for a different purpose, watching you explain it brings a smile to my face :) Flyback diode will take care of the inductive spikes.
This is a recommendation for NE555 or LM555 and the like using bipolar junction transistors. It stabalizes the circuit at the threshold (2/3Vcc). It is not really recommended for CMOS based 555 timers such as LMC555, but it doesn't hurt to have one in a circuit based on CMOS.
You did it again! Another eureka moment about the simple voltage divider. Thank you
This is exactly what I am going to build to control the brightness of the microscope ring light I'm making. Your timing is much appreciated!
One of the best explanations that I have ever seen. Great for beginners! Thanks again
If you reverse the diode connections and add a 1kΩ resistor in the middle, this will give you a constant frequency PWM, which will be a good improvement over this circuit. The capacitor will charge through Rx + 1kΩ, and discharge through Ry + 1kOhm. The total period will be ln(2)x[Rx+Ry+2kΩ]xC which is a constant because Rx and Ry sum up to the potentiometer resistance.
Perfect timing, I was just looking into this. Thank you.
Glad it was helpful!
Diode clamps across motor will protect the 555 to some extent & provide a coasting current to flow through the motor during the pwm switch.. "off" time duration.. especially at low speeds.
Please note that whatever the load is that is connected to the output acts as an integrator, mathematically averaging out the voltage per the percentage ON of given supply voltage (at the output.)
i have an affinity for this circuit too. i might go build one now lol
Great video! I’d love to see a video talking about inductive spikes in circuits like these. Thanks ☮️
With juat a few additional passive components & slight circuit changes ...How about a study on this circuit behaviour....
...1) IF the osc. chg./ dischg. circuit is taken from the jn of motor term.& mosfet drain..through a suitable ( buffered) RC filter..we may get some open loop spd.regulation.
...2) A properly selected current sense resistor in series between Source & 0V
(Vsense = 1/3 Vcc= I mot.limit × R sense) R_sense watts = 4×(I mot.lim.^2× R_sense)watts.
This will provide some extent of current limit protection...
Here the osc.cap is returned to 0 V through the R_current sense res.
Excelent video. Even though I know this circuit, and have built it for a different purpose, watching you explain it brings a smile to my face :) Flyback diode will take care of the inductive spikes.
You are right of course about the spikes, I didn't want to get into that in the video
Another great video 👍 best 12.45 I've spent today
Nice video. Always love the classic circuits you should no videos.
Nice.
You need to connect the diodes to the same voltage as the 555 so the 24v doesn't kill the 555 going into input ppins
Always great to have the drawn schematic and working breadboard circuit. Q) Cntl Pin #5 to GND with cap is doing what? Thx.
Just holding it low.
This is a recommendation for NE555 or LM555 and the like using bipolar junction transistors. It stabalizes the circuit at the threshold (2/3Vcc). It is not really recommended for CMOS based 555 timers such as LMC555, but it doesn't hurt to have one in a circuit based on CMOS.
@@eliasgeorge8534 , excellent info. Thanks. I will test this.
@@learnelectronics , thanks. Since caps don't pass DC, I'll have to think about how this would work a bit more. Cheers.
What other types of signals beside PWM are averaging voltages? make a lesson about it averaging voltages
I prefer to use a zener diode and a resistor.
lets goo, ive been waiting for upload :)
By removing a single diode you can also make this a single pulse circuit
You can make a single pulse by removing the pins 2-6 jumper too.