author

JohanH44

5
Inbox View Profile
4Instructables3,277Views16Comments

Tell us about yourself!

Achievements

  • JohanH44 commented on bluebird129's instructable Clothespin Snowflake
    Clothespin Snowflake

    Real snowflakes have six arms, not eight arms. Nevertheless, these are really beautiful. And probably more beautiful than if they had only six arms.

    View Instructable »
  • JohanH44 commented on arpruss's instructable Copper Pipe Glockenspiel
    Copper Pipe Glockenspiel

    You can use just any notes for "Twinkle, Twinkle Little Star". Starting at C, it goes C C G G A A G F F E E D D C. Starting at G, it goes G G D D E E D C C B B A A G. Starting at any other note requires a chromatic glockenspiel (the model with a 2nd row corresponding to the black keys of a piano), like A A E E F# F# E D D C# C# B B A.There's no original, "correct" note to start on. It's a French traditional song. I think Mozart wrote his famous variations on the theme in the key of G.

    What a great instructable! I was going to do a similar project. I already bought some "semi hard" chromed copper tube. The semi hard means probably that there are different hardnesses of copper tube. The harder, the better for this project, I assume. And the chrome surface might add some clarity to the sound. After deciding to do the project, I found that there's a contest about creating instruments, which made me start writing an instructable. Then I found this eight years old instructable. I won't re-write an instructable (instead I have some other instrument projects for the contest), but I'll most certainly remake this project and comment. It will be a chromatic glockenspiel. I even had a name for the instrument: celestina. Derived from celesta, because of its heavenly sound.

    View Instructable »
  • Arduino really is about doing. Decide what to do, not what to learn. Something you manage with your present skills. Expand it just a little, enough to include something new to learn. That way you create a need for learning.

    View Topic »
  • Google told me the L293D shield is for 4 DC motors with speed control and 2 servos. It uses probably 10 pins. One DC motor with speed and direction control needs two pins. The L293D shield doesn't look like your shield. But if you insist using it, you could try to connect the stepper according to this image.The '-' wire from all 4 motors would go to a common ground, like the GND terminal. The '+' wire from each motor go to M1+, M1-, M2+ and M2-. Then you still have two servo ports. Put a led to the servo signal and servo '-'. The third LED has no place on the shield, unfortunately, but there should be some pins left that you can use. All the digital I/O pins are numbered 0 - 13. Just solder to a pin that is not used for the servos or the motors.IIRC, M1+ and M1- are just transistor powere…

    see more »

    Google told me the L293D shield is for 4 DC motors with speed control and 2 servos. It uses probably 10 pins. One DC motor with speed and direction control needs two pins. The L293D shield doesn't look like your shield. But if you insist using it, you could try to connect the stepper according to this image.The '-' wire from all 4 motors would go to a common ground, like the GND terminal. The '+' wire from each motor go to M1+, M1-, M2+ and M2-. Then you still have two servo ports. Put a led to the servo signal and servo '-'. The third LED has no place on the shield, unfortunately, but there should be some pins left that you can use. All the digital I/O pins are numbered 0 - 13. Just solder to a pin that is not used for the servos or the motors.IIRC, M1+ and M1- are just transistor powered equivalents to two digital pins. When the M1+ pin is high and the M1- pin is low, you have a positive voltage at M1+ while M1- is connected to the ground (it's not negative potential). And when M1- pin is high and M1+ pin is low, it's the other way around. Both M1+ and M1- pins can be high at the same time. This should get both motors connected to the M1+ and M1- running.

    View Topic »
  • I'd start with Arduino and gradually make use of everything you have there in various Arduino projects. Coding happens in Arduino. Arduino again connects easily to electronic components. Teach basics like Ohm's law creating interesting circuits including your resistors, voltmeters etc.

    View Topic »
  • JohanH44 commented on Essort's instructable Talharpa / Juhikko
    Talharpa / Juhikko

    Thank you for sharing! It's a beautiful instrument. But please check the Finnish spelling. It's called jouhikko.

    View Instructable »
  • JohanH44's instructable Wildfire's weekly stats:
    • Wildfire
      109 views
      0 favorites
      1 comments
  • JohanH44 commented on JohanH44's instructable Wildfire

    Here's an error! There is no binary file in the file list. The last file is not the binary file as I thought, but a temporary file with no use. Don't download it.

    View Instructable »
  • JohanH44's instructable Paper Cherokee's weekly stats:
    • Paper Cherokee
      435 views
      2 favorites
      2 comments
  • JohanH44 commented on JohanH44's instructable Paper Cherokee

    Me too. There's only so much fun in competing in length of flight, when throwing paper gliders. This is something different.

    View Instructable »
  • JohanH44 entered Paper Cherokee in the Paper Contest contest
  • Draw a background.Make a new layer with transparency. Draw your paper. Add the text in black.Mark the black text with the "Select by colour" tool (Gimp has a tool with that name). Press delete. Now the letters became transparent (holes in the paper).Rotate the paper layer. Make a copy of the paper layer. Turn the paper black. Use the curves tool for that (Colour->curves). Place the black copy underneath the paper layer. Move them a bit from each other. Now the black layer looks a bit like a shadow.Add some blur to the shadow.

    View Topic »
  • I'm about to start a very similar project. I have a vacuum cleaner with a slide for speed control. I haven't checked yet what component the slide is adjusting. If it is a potentiometer, I bet it would be possible to switch to another potentiometer to even go for lower speeds, as long as the motor still runs. The most interesting solution would be to add som PID control, getting input from the organ wind chest (its pressure) and putting the output to the electronic speed control of the vacuum motor.But my first thing to solve is whether I could use cheap hobby servos instead of solenoids. The reed organ I will rebuild needs very little pressure on the key, maybe 0.3 N while movement is some 20 mm. Roughly calculating a hobby servo might have specs like 3 kgcm, that is 30 N on 10 mm. And th…

    see more »

    I'm about to start a very similar project. I have a vacuum cleaner with a slide for speed control. I haven't checked yet what component the slide is adjusting. If it is a potentiometer, I bet it would be possible to switch to another potentiometer to even go for lower speeds, as long as the motor still runs. The most interesting solution would be to add som PID control, getting input from the organ wind chest (its pressure) and putting the output to the electronic speed control of the vacuum motor.But my first thing to solve is whether I could use cheap hobby servos instead of solenoids. The reed organ I will rebuild needs very little pressure on the key, maybe 0.3 N while movement is some 20 mm. Roughly calculating a hobby servo might have specs like 3 kgcm, that is 30 N on 10 mm. And the speed is some 0.2 s on 60 degrees. With a servo horn of 20 mm turning 60 degrees I get a movement of 20 mm. With a horn of 20 mm I lose half of the force, so I have about 15 N. Now I could make the movement faster by turning only 30 degrees and doubling the horn length. That leaves me at 7.5 N. If the speed is not enough, I still have a way to go when the required force is only 0.3 N.Bottom line is that a hobby servo seems to be a considerable alternative to a solenoid. Is it? Have I missed something? The hobby servos might not be as reliable in the long run. Lots of cogs spinning during the flight of the bumble bee.

    View Instructable »
  • The sensor reads the amount of infra red light. Nothing more. The rest is in the code. You might have a lot of infra red light around you. I tested the sensor while the lights were on in my room. The lights flicker with 50 Hz (Finland). This I could see in the output from the sensor. So to get a good reading from the sensor, I calculated the average of all readings during a 20 ms period. Plotting a curve of the averages I got, created a nice graph showing how my blood vessels in my finger tips pulsed with my heartbeats. If there are other significant infra red noise sources, you might need to smoothen the graph further. After that it's about recognising rising slopes or peaks or whatever looks easiest to get the rate. Some count beats in a 15 s period and multiply it with 4 to get the BPM…

    see more »

    The sensor reads the amount of infra red light. Nothing more. The rest is in the code. You might have a lot of infra red light around you. I tested the sensor while the lights were on in my room. The lights flicker with 50 Hz (Finland). This I could see in the output from the sensor. So to get a good reading from the sensor, I calculated the average of all readings during a 20 ms period. Plotting a curve of the averages I got, created a nice graph showing how my blood vessels in my finger tips pulsed with my heartbeats. If there are other significant infra red noise sources, you might need to smoothen the graph further. After that it's about recognising rising slopes or peaks or whatever looks easiest to get the rate. Some count beats in a 15 s period and multiply it with 4 to get the BPM. I simply measured the milliseconds between each beat and averaged the resulting BPM with two or three previous ones.So the sensor doesn't give you a BPM value. It only gives a value telling how much IR the photo transistor receives.

    View Instructable »
  • Great idea, especially being analog. Nevertheless, my suggestion for development would be replacing the spinning motor with static coils. The coils (several) would be controlled by a microcontroller. The tip of the top would be a pen. Varying the current strength in the coils will control the position of the spinning top, which will draw something, say tarot symbols at a spiritistic seance.

    View Instructable »
  • JohanH44 commented on lingib's instructable CNC Dual Arm Plotter

    My servo is a Turnigy TGY90S Metal Gear Servo 1.8kg / 13.4g / 0.10sec. I just happened to find them in a 2nd hand market, so they were by no means hand picked for this project. I guess the stepper motor approach is way better. I picked the 1:1 ratio for simplicity, too. But then I realised that the maths are not that harder for any ratio! A² = B² + C² - 2BCcos(a) where A is the elbow-pen-arm and a its opposite angle you want to find.I have yet to "calibrate" my servos. They don't turn a full 180 degrees, though my code expects them to do so. But my tests show that the servos (with minimal load) rotate each time very precise to same position for any given angle.To minimise friction at the elbow joints, I've thought of using flat bearings. And neodym magnets 1 mm fr…

    see more »

    My servo is a Turnigy TGY90S Metal Gear Servo 1.8kg / 13.4g / 0.10sec. I just happened to find them in a 2nd hand market, so they were by no means hand picked for this project. I guess the stepper motor approach is way better. I picked the 1:1 ratio for simplicity, too. But then I realised that the maths are not that harder for any ratio! A² = B² + C² - 2BCcos(a) where A is the elbow-pen-arm and a its opposite angle you want to find.I have yet to "calibrate" my servos. They don't turn a full 180 degrees, though my code expects them to do so. But my tests show that the servos (with minimal load) rotate each time very precise to same position for any given angle.To minimise friction at the elbow joints, I've thought of using flat bearings. And neodym magnets 1 mm from each other to keep the joints together. No bolts! No contact point other than the bearing balls. This I'll let wait until I get hands on a 3D printer. With the printer I will create 1:2 or even 1:3 arms with perfectly fits for the servo horns, the bearing beds, the magnets etc.

    View Instructable »