Hi All!
I have built a programmable dummy load inspired by Daves initial one, I think it was episode 102? It is capable of constant current, resistance and power.
This is the link to the Instructable
http://www.instructables.com/id/Arduino-Programmable-Constant-Current-Power-Resist/ I would really appreciate your feedback on the instructable and the theory within.
I have also done my first 3 three tutorial videos on using SPI that I am really happy with, videos are hard to do well, and Dave does it very well!
I just wanted to thank everyone on this forum that has helped me through this process, I have learned an incredible amount and pretty happy with my first real project, schematic and PCB!
Thanks again
Lee
subscribed for a later view.
Only feedback I have so far is the sound quality, not a show stopper but something that could make a difference in the future, I only watch a bit of part 2 since I don't have time until later, so it might not affect the other videos
nice one ! i like it
but probably i would go for better op-amp than lm324 in case of a 12bit DAC/ADC. for example OP07 is cheap and has a order of magnitude lower input offset than lm324 (75uV vs. 2mV).
Only feedback I have so far is the sound quality, not a show stopper but something that could make a difference in the future, I only watch a bit of part 2 since I don't have time until later, so it might not affect the other videos
I agree totally! I am looking into a good mic to use, any suggestions?
but probably i would go for better op-amp than lm324 in case of a 12bit DAC/ADC. for example OP07 is cheap and has a order of magnitude lower input offset than lm324 (75uV vs. 2mV)
Again, I agree totally :-) when I started to fine tune everything, the offset voltage was my biggest limitation, however, some kind people on here helped me significantly with calculating the resistors and capacitors to deal with the phase shift. I haven't looked at the output resistance if that other op-amp but I wasn't capable of calculating it myself at the time. It's certainly something I will do better in my power supply :-)
Thanks again for the great feedback!
Hi All!
I have built a programmable dummy load inspired by Daves initial one, I think it was episode 102? It is capable of constant current, resistance and power.
This is the link to the Instructable http://www.instructables.com/id/Arduino-Programmable-Constant-Current-Power-Resist/ I would really appreciate your feedback on the instructable and the theory within.
I have also done my first 3 three tutorial videos on using SPI that I am really happy with, videos are hard to do well, and Dave does it very well!
I just wanted to thank everyone on this forum that has helped me through this process, I have learned an incredible amount and pretty happy with my first real project, schematic and PCB!
Thanks again
Lee
Subscribed and added to watchlist for tonight's viewing when SWMBO has gone to bed.
Can you set a cutoff voltage on this load? I'm interested in testing batteries and cell health, it would be helpful if the load didn't undercharge them.
Can you set a cutoff voltage on this load? I'm interested in testing batteries and cell health, it would be helpful if the load didn't undercharge them.
Hey Mate
Currently the software doesn't allow it but it is certainly possible! It is able to sense the input voltage and you would be able to write a small piece of code to not let it go below a certain voltage without too much trouble at all. I might even add it to the next software review list
Thanks
Lee
Hi,
I am thinking of running some more PCBs, would anyone be interested in buying one for $10?
Thanks
Lee
Hi Lee, Put me down for 2. I'm in Perth,
Thanks,
Greg
Didn't Dave have a go at your board in one of the recent mailbags?
Didn't Dave have a go at your board in one of the recent mailbags?
Have a look for yourself. Starts at 19:25 if the link doesn't do it automatically
http://youtu.be/E9lYHIAZeTc?t=19m25sSound good everyone, I will order some more and let you know when they arrive.
Thanks
Lee
i already have the board and its a nice i recommend , already soldered some of the parts awaiting some other parts which are on backorder, will try to post some picture of it
regards and thanks to Mr Wigman
Hi all!
My new boards have arrived, they are $10 each plus postage.
If you are interested please send me a personal message to arrange payment and shipping.
Thanks
Lee
Thanks Lee, mine arrived today safe and sound.
Hi all,
I have decided to start working on a revision C. The list of improvements to be investigate are,
- Fully simulate then test the AD8360 as a replacement for the lm324.
- Look at replacing the relay switch over with an OR based system.
- Amplify IOUT to make better use of the of the ADC resolution.
- Redesign the board to better suit an enclosure.
- Move to an SPI based TFT screen or graphic LCD for a more user friendly display.
- Incorporate reverse polarity protection for the inputs.
- Upgrade to a PWM based fan.
- Improving USB isolation.
- Improve analog and digital ground planes.
These changes are still being investigate and will be quite a while off implementation. If anyone has any suggestions then please reply with your suggestions.
Thanks
Lee
Hi Lee,
Few suggestions:
- Switch to another AVR, e.g. 2560, 32k (even without bootloader) is a little small to improve software features (at least for my alternate code). Also, TFT support will suck a lot of flash space. Sure, an extra chip will be required for USB link (who said FTDI ? )
- Use two free-up pins to add support of an INPUT relay.
- About the PCB drawing, it would be great to add some footprints for external connections for the MosFET (I personnaly use two in //, externally bolted on a huge heatsink), temp sensors and hi power 0.1R resistor (all these parts are also bolted on that huge heatsink).
Of course, it's only my 0.02$
Cheers.
---
Daniel
Hi all,
I have decided to start working on a revision C. The list of improvements to be investigate are,
- Fully simulate then test the AD8360 as a replacement for the lm324.
Hi Lee,
I think you've meant AD8630? Could you explain a reason for this change please?
Anyway great project
Regards
Adam
Yep, that's what I meant sorry :-)
The main reason is better offset voltage. There are a lot of other things to consider with the Opamp but that's my main reason for the upgrade.
I haven't done muck work on this yet I'm afraid but a couple of people have helped tremendously in another thread helping me workout the feedback compensation so as soon as I have time I'm back on it :-)
Thanks
Lee
Hi,
Here is a picture of the "finally" finished DC Load.
Cheers.
---
Daniel
wow, beautiful job f1rmb!