Building a SpurtBot

Let's Make Robots Tutorials
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41

Hello Hartmut,most of the

Hello Hartmut,

most of the components I ordered arrived.

The cellphone vibration motors are weaker then I expected and the weight is impossible to remove even though I searched for some tutorials before ordering them. I tried pinching them off and squeezing the weight appart, the only thing left to try is to hammer the shaft out of the weight, but   the thin nails I had here where all too soft :-/

The transistor and LDR with the bc337-25 seem to do the job nicely, changing the motor speed from very slow to fast.
I use these LDR for now, http://www.aliexpress.com/snapshot/6020160679.html

I found a cheaper source for motors that seem to be like the one I had here to play around with,
http://www.aliexpress.com/item/20pcs-lot-original-Vibrator-Vibration-Motor-for-iPhone-5-5G-motor-free-shipping/1667649192.html
but I do not want to run into similar problems again…
These cost 30 eurocent in larger quantity, http://www.neuhold-elektronik.at/catshop/product_info.php?cPath=96_97&products_id=4807 - but also draw a lot more current so I am not sure if I can use  the ordered components…

Any advice on alternatives, easy to source and inexpensive motors?
I have a few old computers with CD drives at hand, but not enough to provide motors to a whole class.

 

I also ordered a few other components such as http://www.aliexpress.com/snapshot/6028924819.html and http://www.aliexpress.com/snapshot/6020160673.html so hopefully something works out…

-Marcus

42

Hope it Helps …

Hi Marcus, my quick & dirty answer (since I never tried out your devices):

I would not have had the courage to think about vibration motors. But since you have them now maybe you can try to use them as they are. Vibration would not harm much the traction I argue. Maybe you can try to reduce the vibration a bit by using abrasive paper to grind the vibration mass as much as possible while the axis is spinning at high speed. - No idea whether it helps

Concerning the TCRT5000 you need to try out whether it can discriminate between white and black paper. In infrared it could be fairly a similar reflection. And maybe you need to remove or at least shorten the separator between LED and photor transistor to ensure that reflected light can reach the receiving photo transistor.

If you want to use a rubber belt from motor axis to a ball bearing (wheel) for traction you must ensure that both axises are strictly parallel since otherwise the rubber belt would slip off.

Are you sure that your motors need less than 100 mA? Otherwise you need other transistors, those which tolerate higher collector current.

Good luck  –  Hartmut

 

 

43

Hello Hartmut,the current

Hello Hartmut,
the current motors are too weak to attach anything to the shaft - even the rubber band.  With the weight they bounce around too much… If I could just find an easy way to remove those things, I could let it drive directly on the shaft.
I have had another idea I am going to try out tomorrow, hopefully it will not damage the motor.
…
Right now the motor will almost stop if held close to a dark surface while spinning fast over wooden laminate flooring. Just with room light. Suprisingly.

The motors are tiny, sadly even smaller then the one I had before ordering these - I find different specifications from different sellers, but they should be a fair amount under 100mA. The BC337-20 still work and do not get hot either, not even when I use three cells.

44

Motors

Hi Marcus, please let me repeat it: You need a motor with high torque, low speed, low current, long shaft.

Andrew and I myself have tried out lots and lots of motors. You can choose either to select one of those we found or you can try to find another one, but be aware that it can take you weeks and bucks a lot. So we did. :slight_smile:

Good luck  –  Hartmut

 

 

45

Built 3 times, three ways, still can’t get it to work

Hey IGG,

Love the depth and detail in this and the instructables version I send my students to, but after buying a lot of parts and building 3 of these that refuse to work, I’ve had to hit pause on future use of this design until we can debug it.

We have built the circuit as instructed above to the letter, three times, but can only occasionally get even a turn or two from the sensor/NPN connected motor. We have experimented with various sensor heights, with differing reflective/absorptive materials, varying resistors, fine tuning with varistors, replacing with fresh QRD 114’s, replacing fresh BC337’s, bread-boarding, soldering …nothing works.

We also tried the previous and following designs that all depend on the QRD 114  and BC337 combo, with additional resistors)

The only part that we have that differs is the motors, but on the breadboard we also tried lights and piezo buzzers to see if the “time to turn” signal was getting through and it just isn’t.

Is there any way to know if our entire bag of BC337’s or entire box of QRD 114’s is bad?

All the components are measuring fine and the continuity is good to each connection.

Do they make a spec version of either of those parts with vastly different performance characteristics than the ones listed above? (but still refered to generically by those part numbers)

I’m grasping at straws here.

We tried the 10K pull down, it had no effect, and I’m starting to question the QRD 114 as a robust solution since use of discrete components and the CNY 70 show up in many more designs. (though there is no way to tell if any of them provide more reliable results)

I have a hard enough time getting a few dollars for my tech budget at the school each year so this has been a real black spot on our efforts to grow the electronics portion of three different classes. The kids are all  getting tired of these light/dark based logic circuits that don’t work (several of the laser trip wire circuits we have tested have also been a bust).

Should this be a 3v project, so many others are 9v?

Are light sensing projects just notoriously fraught with unaccounted for variables, or is there a way to add more parts to this design for increased reliability?

Should I give this another try and order just a pair of CNY 70’s or try subbing in a Schmitt trigger to mimic other LFR deigns we have seen?

Could we add another QRD 114 and/or BC337 ( one or more) to improve the function?

 

Is there a troubleshooting tip we have overlooked?

 

Ultimately I have to decide in the next week if I can even teach with this pile of parts or toss 'em in the bin and wait another year to get something else, other components perhaps, or just a whole new project.

46

Found it …maybe?

AHA!!

…Found it …maybe?

The amplification is higher in the BC337-40 originally (and fully) specd on the original SPURTbot plans from Rostock, I will try getting those specific -40 versions and see if they work. The Jameco link above does not specify the -40 model of BC-337’s, so we might have gotten the grab-bag roulette variety and ended up with the -25 model which is no good for this circuit?

see page 2 from Rostock, of course they are also using the CNY70

Is is possible we just got the wrong BC-337’s?

How much better is the CNY70 than the performance of the QRD1114?