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| Chrono Mark II Assembled |
- The fact that it was not a round tube but a teardrop and therefore may not always line up with the rifle and look a bit odd.
- An external charger circuit was required to charge the internal battery.
- The switch was mounted at the other end of the tube from the electronics and was a bit of a pain to wire up and assemble.
The main reason for the teardrop design was to fit in the electronic modules with the central tube so I needed to come up with a design where I could place the modules and battery around the perimeter of the tube whilst keeping the overall diameter as small as possible.
I also wanted to add a charging circuit inside the tube so there was only one part to worry about so you could just plug it into a phone charger to charge it. If I could get all this inside the tube, along with a switch located at the same end as the electronics then it would be a big improvement IMO.
First test was putting the modules around the tube .... using Tinkercad I messed around with all the modules trying to fit them in.
Having got them to all fit in a round base I set about figuring out the charging the battery and powering the Nano from the 3.6V battery as the IR receivers were specified to use 5V.
After a good Googling around for some modules I finally found some modules that fit the bill, one to convert 3.6V to 5V and another to charge a single lithium cell from 5V. These module need to be pretty small and I wanted them to be on a single PCB to make wiring up the modules easy so I designed a PCB to mount them on and had the idea to attach the PCB to the switch which would be securely screwed in to the base.
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| Power PCB Circuit |
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| Design layout |
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| Final PCB |
Some More Images
| Item | Link | Cost |
| Pololu 5V Step-Up Voltage Regulator U3V12F5 | Link | £3.32 |
| DD08CRMA Mini 5V 1A Lithium LiPo Charger Module | eBay Link | £1.97 |
| Mini Miniature On/On 6 Pin Slide Switch DPDT | eBay Search Link | ~£0.40 ea. |
| Power PCB gerber files | Link | £0.00 |
| 3D Print files for carrier and tube | Link | £0.00 |
8 comments:
Looks good buddy
Bb sensor is build on phototransistors?
And where i can get full documentation of this project?
Tylko,
All the details required are in this blog, the differences between thisdesign and the previous designs are described in this post.
Feel free to ask specific questions in the comments if it's not clear.
Could you please post STL files for this enclosure?
Thank you!
Find them on thingiverse https://www.thingiverse.com/thing:2784926
Hi Gadjet!
I built your IR chrono and also made some minor changes to the App. Thanks for your help in the past.
I would like to ask for your input. Trying to find or build a magneto-sensor for a barrel mounted chrono to use instead of the IR sensors for the benefits of less interference and maintenance. There is already a commercial product out there that uses electromagnetic sensors. I am trying to reverse engineer the pick up sensor. Could you look at the last post by Tom S (me) which explains it all. Thank you for any assistance!:
https://forum.allaboutcircuits.com/threads/ballistic-chronograph-project.134901/#post-1252183
Hi,
I had a look at the post but I don't have any answers for you I'm afraid, I use an inductive sensor for setting the height on my 3D printer which uses an aluminium bed, maybe one of these types of sensors may work although I'd guess it may not be quick enough for it's digital output to react, maybe you can get an inductive sensor with a pure analog output? maybe something used as an ABS wheel sensor on a vehicle? (magneto reluctance sensor?)
Hope this helps, if you find something then please feedback, the optical solution works fine for my 12ftlbs air rifle :-)
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