Peter Wallers Robot Ramblings

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peterwaller
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Re: Peter Wallers Robot Ramblings

Post by peterwaller » Fri Jun 07, 2019 2:37 pm

One of the biggest problems I find as I get older is starting more and more projects without necessarily finishing any.
Someone on here mentioned the RZ7899 motor driver that looks really good.
It is similar in spec to the DRV8872 I use in my latest design but doesn't have the pad under the IC that has proved difficult to solder by hand with an iron.
Added to that the fact that the small orange receiver is now obsolete (even though I have a good supply of them) I decided to do a new board using the RZ7899 and the lemon receiver.
I ordered some boards yesterday from PCBWay and will let you know how they work out assuming I do finish this project. :roll:

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Re: Peter Wallers Robot Ramblings

Post by MarkR » Fri Jun 07, 2019 2:54 pm

I'm using the rz7899 in the Malenki ESC. It's a single channel H-bridge in a soic8, I don't find them to be difficult to solder unless the board has too much copper around (particularly the 2 ounce copper).

The nice thing about it is that it has a good wide voltage range, quite big claims of max current, and doesn't need an auxilliary power supply; there is literally only one supply pin, which drives the chip's guts as well as the motors.

I also haven't managed to break one yet :)
Robot: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?

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Re: Peter Wallers Robot Ramblings

Post by peterwaller » Tue Jun 11, 2019 6:13 pm

The PCB's have arrived that's just 5 days from uploading the file.
Here it is next to the lemon receiver.Image

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Re: Peter Wallers Robot Ramblings

Post by MarkR » Tue Jun 11, 2019 7:11 pm

Looks good, nice big rings around those through-hole pins, much bigger than the ones on the RX.

What design software did you use?

I am assuming it's a single-sided layout, IC3 and IC4 are the rz7899 ? I see the pads connect 5-6 and 7-8

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Robot: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?

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Re: Peter Wallers Robot Ramblings

Post by peterwaller » Tue Jun 11, 2019 8:15 pm

It is a 2 layer circuit board with components just on one side.
I have a very old copy of Protel Client98 (1998 vintage) that I have to run on an old Vista machine because it won't run on Windows 10.
I am just trying a later version of Protel DXP which does seem to run on W10 so I will probably migrate to that.
One problem they both split the drilling data on the gerbers into two files that the PCB manufacturers can't use but PCBWay can just use the protel PCB file direct so it is not a problem.

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Re: Peter Wallers Robot Ramblings

Post by peterwaller » Sun Jun 30, 2019 8:38 am

I fitted the new controller in my old Flippant which had died.
It ran faster than on the old controller and actually ended up being my most successful entry in AWS58.
Very pleased with how it ran.

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Re: Peter Wallers Robot Ramblings

Post by MarkR » Sun Jun 30, 2019 7:24 pm

Good stuff Peter, so we rate the rz7899 as "combat ready" ?

I also ran Stacie with the rz7899-based Malenki-ESC, and it ran nicely, it did a lot more heavy duty work in the kids' arena :) , and was still working at the end.
Robot: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?

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Re: Peter Wallers Robot Ramblings

Post by peterwaller » Thu Jul 25, 2019 8:48 am

My drum spinner Anticyclone has terrible gyro effects when turning due to the large mass and speed of the drum. I have redesigned it with a much lighter 3D printed drum which has 3 double ended Titanium blades with an indirect geared down belt drive. The robot is also my first try at printing in Carbon X a carbon fibre filled nylon material.
Image
Below is a video of it turning with the drum on full throttle on a 3 cell battery.
https://youtu.be/JixlPH39ElA

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Re: Peter Wallers Robot Ramblings

Post by Wigs » Thu Jul 25, 2019 9:46 am

Love it

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Re: Peter Wallers Robot Ramblings

Post by peterwaller » Mon Aug 12, 2019 1:28 pm

Just been doing a couple of repairs from Roboshowdown both of which can be partially blamed on poor maintenance.
The weapon motor in Anticyclone was the one that came out of Combatant with a broken shaft. As a quick repair I replaced the 2mm steel shaft with a carbon fibre one which I was going to replace but forgot. This broke and the resulting current seems to have overloaded the on/off switch. I have now fitted a steel shaft and just need to replace the switch.
Flippant had sustained damage to the self righting tynes at the AWS when I picked up a drum spinner but I thought they would be OK.
One was quickly taken off in an early bout and then tacked back on with superglue and sellotape but Morning Dew soon detached that again and half of the next one. They were printed in Polycarbonate which showed signs of delaminating so I have reprinted them in Carbon X.
Unfortunately this was slightly heavier than before so I have had to thin the armour somewhat and reprint it so I have done that also in carbon X and it has come in at 143 gms.

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