Sensor(s) to determine if plastic pickleball has hit target

Thread Starter

GrampsFish

Joined May 22, 2020
29
A thought, its easier to make a receiver narrow beam than a transmitter.
so a light along two sides, cna be detected by detectors on the other side.
just pit a "tube" on the receiver. Does not evne have to be a tube, just two holes separated by a few mm works.

Its much easier to detect AC signals than DC ones, so amplitude modulate the emitters, means you can use an AC coupled filter as the receiver, with filtering if needed . If you MCU is fairly fast, such as a tensey Arduino, then you can apply filtering of the signal sin the MCU, to avoid false detection,

Also using the receivers like this, allows you to easily have a none linear array, you just have to move the holes / receivers.
Thanks! So I'd be setting up a 10" long light source on the left side of my 4' wide x 3' high wall, and an 18" long light source at the bottom (maybe a strip of LED lights?). And then recess each of the receiving sensors (4 on the right side and 7 on the top) so the sensors would be far enough back that ambient light wouldn't affect them, but the light source would?
 

Thread Starter

GrampsFish

Joined May 22, 2020
29
I dropped a ball from 5' on to hard floor & sensor on hard floor, rebound was at same height
to both.
If I wanted to test how this might work before I try my hand at putting together an electrical circuit, could I make the Velostat and aluminum foils "sandwich" and then use my multimeter to check for continuity between the 2 sheets of aluminum? Would the multimeter beep each time the target was hit, much like it beeps any time the two probes touch?
 

Bernard

Joined Aug 7, 2008
5,784
When I monitored target resistance with ohmmeter , a ball drop was just a slight flicker. That is why a pulse stretcher is needed- like a 555 or a comparator.
 

Deleted member 115935

Joined Dec 31, 1969
0
Thanks! So I'd be setting up a 10" long light source on the left side of my 4' wide x 3' high wall, and an 18" long light source at the bottom (maybe a strip of LED lights?). And then recess each of the receiving sensors (4 on the right side and 7 on the top) so the sensors would be far enough back that ambient light wouldn't affect them, but the light source would?

Thats about right,
it could be just a couple of IR leds, and a diffuser ( tissue paper behind a bit of perspex ),
does not have to be constant over the length of the diffuser,

May be try it with a visible led first for confirmation,

https://learn.adafruit.com/ir-breakbeam-sensors

http://www.righto.com/2010/03/detecting-ir-beam-break-with-arduino-ir.html
 
A couple of comments:

I doubt you want to delve into surface mount.

The R and K are also used as decimal points. 1K5 is a 1.5K ohms.
10n is 10 nF or 10E-9 or 0.01 uF; u=uF;
Generally you don't see nF. uF and pF are common. Ancient abbreviations were MFD and uuf
When I was in school Farad value capacitors were impossible to achieve.

Component search engines for digikey and Mouser are best using "resistor" and not "56 ohm resistor"

RV1 is resistor Variable #1

The Volume Pot needs to have a LOG or Audio taper
Tone should be a linear taper.

The higher the voltage, the greater the volume, so probably a 12V wall wart. Watch polarity. 5.5/2.5 and 5.5/2.1 are common coaxial diameters.

Capacitors have types and voltage ratings. 2x the supply voltage is always good,
C2 is ceramic. C1 is Metalized Polyester C2 should be placed "close" to the IC pin.

R1 could be 1/4 or 1/2 W
R2 should be checked. Power needs to be greater than ((15-0.6)^2)/56. resistors come in finite ratings of 1/8, 1/4, 1/2/ 1W etc,
The metal oxide varient is best in this application. The reason why the 0.6 to 0.7 is a diode drop of the transistor in the IC.
For this calculation, you can easily assume zero.

The circuit may not be able to drive a speaker. There are plenty of amp PCB's on ebay.
make room for a capacitor in series with the output of pin 3.

Construction techniques: Look up strip board. You generally cut traces and use jumpers.
Teflon tubing and solid uninsulated wire is easy to use, but a roll of PTFE tubing is expensive.

Then there might be a DC Coaxial jack (panel mount?), spacers, knobs, Maybe a sub-mineatire jack for the spaeaker, possibly screw terminals too. An IC socket.

A "connector" for your morse key.

Further down the road, you can consider 0.100" pitch AMPMODU connectors. these would connect your tone and volume controls, power and output. You could consider making an "extension cable(s)' to have more room to work outside the case to work.

Then tools:

The case and PCB have to be big enough and you might have to add an amplifier.
 

And the second question is, could the code-practice oscillator circuit be easily adapted to include an L.E.D. counter and an adjustable timer? Right now, I'm not looking for any guidance on how to add a timer and a counter to the circuit - just interested in knowing if it would be very difficult or expensive to do.
The "Devil" is hiding in the details.

@GrampsFish

Come up with some sort of specs for your counter and timer. How should it behave?
 
Last edited:

Bernard

Joined Aug 7, 2008
5,784
In making the Velostat, Vl , sensor keep the resistance as high as possible. The biggest problem
is the attachment of Vl to base. Might add a separating strip of heavy paper , .005", around the target foil. With a 7" test strip, no spacer = 3k, with spacer= 7k.
One half oz. plastic ball drop test. 5.1 V supply, 4.7k from + to Vl, other wire to battery -. Scope
gave 4.5V before drop & .5 V @ 2' drop, OK input to a 555. Pulse about 15ms.
 
Last edited:

Thread Starter

GrampsFish

Joined May 22, 2020
29
The "Devil" is hiding in the details.

@GrampsFish

Come up with some sort of specs for your counter and timer. How should it behave?
I've been pondering this, and while a timer is on my "it would be really nice to have" list, I don't think the counter is feasible with the amount of time and money I'm willing to invest in this.

For the timer, I'd be happy if it was adjustable from 1 minute to 10 minutes - either infinitely or in 1 or 2 minute increments. There'd be buttons for Start, Pause, Reset, and Repeat. Pressing "Pause," "Reset," or "Repeat" stops the timer. "Reset" and "Repeat" set the timer back to its initial setting, with "Repeat" starting the timer again and "Reset" having the timer doing nothing until "Start" is pressed. When the timer finishes counting down, a sound is generated for around 2 seconds. I suspect it might be easier for me to buy a cheap timer than to re-invent the wheel and add the timer into the target's chime.

The reason I don't think the counter is feasible within my time and budget takes a bit of explanation:

I started playing PickleBall just a few weeks before the virus shut everything down, and decided to build a 4' wide by 3' tall practice wall so I can get some exercise and improve my skills while waiting until it is safe to be on a PickleBall court with other people.

Just plain hitting the ball against the practice wall is boring, so I drew an 18" wide by 10" high target on the wall, and created some 5 minute long "games" to play. All the games require me to hit the ball and strike the target, but in order for the strike on the target to count, I have to do certain things before I hit the ball.

In one game, for example, I put a mark on the floor about 7 feet away from the wall. I stand behind the mark for the first hit on the ball, and then step in front of the mark for the second hit. After that, I alternate - one hit from behind the mark and then one hit from in front of the mark. In order for a strike that hits the target to count, both of my feet have to be on the correct side of the mark before I hit the ball.

In another game, I don't use a mark on the floor. The criteria is that I have to alternate between hitting the ball on one bounce and hitting the ball "on the fly," before it bounces.

In both games, the counter would need to increment only when I hit the target after having met the other requirements of the "game."

Having a chime sound when I hit the target is going to tell me that I've hit the target (in some games, up to over 300 times in a 5 minute period). While I can easily determine whether or not I've met all the game requirements before striking the ball and can increase my count when the chime sounds, I don't see an inexpensive way to do that automatically.

One of the guys I played PickleBall with expressed an interest in also building a wall, and we've talked about inviting others in our group to join in some competition with these games. I put together a video that shows the 10 "games," and it might help you get a more clear picture of what I'm doing if you watch 10 or 15 seconds of the video. You'll find it at

I made the video a few weeks ago, when we were talking about counting only consecutive hits on the target, but we've decided to change to the cumulative number of hits instead... providing we're capable of remembering whether we're at 150 hits or 250 hits as we're trying to hit the ball while meeting all the criteria of each particular game.
 
Last edited:

Thread Starter

GrampsFish

Joined May 22, 2020
29
For possible suppliers, what country are you in?
I'm in a western suburb of Chicago, Illinois, USA. My preference is to find an electronics store where I can talk with someone face-to-face, show them a copy of the circuit and a bill of materials, and then walk out of the store with all the components in hand.
 

Thread Starter

GrampsFish

Joined May 22, 2020
29
In making the Velostat, Vl , sensor keep the resistance as high as possible. The biggest problem
is the attachment of Vl to base. Might add a separating strip of heavy paper , .005", around the target foil. With a 7" test strip, no spacer = 3k, with spacer= 7k.
One half oz. plastic ball drop test. 5.1 V supply, 4.7k from + to Vl, other wire to battery -. Scope
gave 4.5V before drop & .5 V @ 2' drop, OK input to a 555. Pulse about 15ms.
Thanks! The "outdoor" pickleball I use weighs 0.9 ounces, so it sounds like I'm in good shape - especially since I sure hope the ball I hit will have more velocity than a dropped ball.

As I understand what you're suggesting about the strip of heavy paper, I might cut four strips of the heavy paper that were 1/2" wide and each the length of one of the Velostat edges, fold the paper in half so it was 1/4" wide, cut both ends of the strips going on the top and bottom to 45 degrees (to reduce the thickness where the strips overlap at the corner), and then slide the strips over the edges before assembling the "sandwich" of materials. I think folding the paper would make it easier to make sure it stayed on the edges - would it cause any issues with the performance of the Velostat?

Also, one of the online suppliers I've seen offered to send the Velostat on a roll (instead of folding it) for a $10 roll charge. Regardless of where I order the Velostat, should I be concerned about whether or not the material is folded for shipping?
 

Bernard

Joined Aug 7, 2008
5,784
Nice video. There should lots of electronic stores in Chicago; maybe a Allied Electronics retail store?
Might build the sensor first. I would use 1" strips with all sheets 12" X 20" except for target of 10" X 18".
Just checked my Velostat, it still has a distinct crease from folding. For a large sensor that might have a detrimental effect.
It may be worth the extra $10. Ouch. Note that I have never made a large pressure sensor.
It might be possible to detect hits on full board. Board hit & target hit = hit; board hit- no target hit = miss & counter reset.
 
Last edited:
I have this https://www.thermoworks.com/Extra-Big-Loud and it's pretty close to what you want.

1s rather than 1 min. For normal timing operations, you have to push stop twice. If you press it once your in "cookie baking mode".

Anyway, pressing stop once, stops the clock and re-loads the last value. Pressing stop 2x, would also clear the last value.
There are 4 volume values.

Without entering a count-down number and pressing start, it counts up no alarm.

The alarm isn't continuous. It is for a while, but then it beeps every once and a while.

You can start and stop the timer.

I just wore out the start, stop and zero buttons and tried a fix on this and a remote control. Conducto-lube.
Battery connector (spring loaded) is kinda crappy.

9V battery. Their last upgrade had a much better magnet, I'd like to disable the Vol button and keep it at max. IF it powers up at Max, I could put a piece of Kapton tape on the contacts.

Not sure what the volume powers up with a new battery, Removing the PCB, you will disturb the Zebra connector for the LCD. They are always "fun" to align.

====> You can't pause the count.

However, you could:
1. use a white board and write down the value
2. Use a thumbwheel switch to "write" down the value of the clock.

then enter the new value. Then enter it.

You don't even have to do that. Just look at the value. Stop the clock and enter the value. Don't hit start until pause has eded.
 

Thread Starter

GrampsFish

Joined May 22, 2020
29
I know I'm a little late to the party, but have you considered an acoustic pickup attached to the target board, or perhaps a vibration sensor?
Thanks for the ideas. I originally started my search for help with this on Reddit, and the very first suggestion I received there was for an acoustic pickup. In researching the acoustic pickup, I found some vibration sensors.

The issue with both is finding a way to isolate the target area from the playing area so hits outside the target area don't get counted.

The playing surface is a 4' wide by 3' high sheet of plywood. Right now, my 18" wide by 10" high target is hand-drawn on the plywood with an indelible marker. If I were to try an acoustic pickup or a vibration sensor, I believe I'd need to cut the target area out of the playing area and build some sort of sound or vibration isolating frame that would hold the target in the correct location, keep the target in the same plane as the playing surface (so the ball wouldn't bounce funny when it hit the edge of the target area), and have the ball "play" with about the same feel and rebound when it hit the target as it does when it misses the target.

If the Velostat material has minimal effect on the way the ball plays, I think it would be easiest for me to implement. If the Velostat doesn't work out, then I'll need to decide whether to try the sound/vibration setup or some sort of array of lights and sensors.

Thanks again for the suggestions.
 

Thread Starter

GrampsFish

Joined May 22, 2020
29
Nice video. There should lots of electronic stores in Chicago; maybe a Allied Electronics retail store?
Might build the sensor first. I would use 1" strips with all sheets 12" X 20" except for target of 10" X 18".
Just checked my Velostat, it still has a distinct crease from folding. For a large sensor that might have a detrimental effect.
It may be worth the extra $10. Ouch. Note that I have never made a large pressure sensor.
It might be possible to detect hits on full board. Board hit & target hit = hit; board hit- no target hit = miss & counter reset.
Thanks again!

One of my first thoughts when you suggested the Velostat is that I could cut an 18" x 10" piece out of a 4' x 3' sheet of Velostat and then mount both the large sheet and the cutout onto my 4' x 3' plywood playing surface. That would give me a consistent playing surface over the entire board, and I could do something very much like you suggested - I'd wire the 2 pieces as separate pressure sensors and hitting the smaller one would be counted as a hit and increment the counter, while hitting the larger one would be a miss and reset the counter.

My "it is 3 AM and I can't get back to sleep" musings on this setup had me solving the problem of the ball completely missing the 4' x 3' target by adding some sort of timer to the circuit so the counter would reset if there was too long of a delay between hits.

The problem I don't believe I can resolve within my budget is keeping the counter from incrementing when I hit the target area, but haven't met the criteria of the game. If, for example, I'm supposed to have both feet in front of a mark on the floor before I strike the ball and don't, I wouldn't want the counter to increment even if I hit the target.

As far as the folding/rolling - is there any reason I couldn't cut a folded piece of Velostat a hair to the left and then a hair to the right of the fold line, and then mount the two pieces in the target area instead of one larger one?

Thanks again!
 
Top