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Chris Bott - Moderator

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Everything posted by Chris Bott - Moderator

  1. Chris Bott - Moderator
    This is interesting stuff Simon.
  2. Chris Bott - Moderator
    Martin you're right, these days most Rx will have a CPU that works at 3.3v so it's output pulses will be 3.3v "tall". Yes the Servo measures the width of these pulses. It likely does so by having a threshold (slice) voltage, effectively measuring the time that the pulse is above that voltage. In a perfect world the pulses have vertical sides and a flat top so the servo will work if the pulse height is greater than the slice voltage. (And won't work at all if pulse is lower) In the real world the pulses can have quite rounded corners, probably more pronounced with long extensions, so if the slice voltage is up in the rounded area things can start to get quite jittery.
  3. Chris Bott - Moderator
    Some radios (maybe most) provide a servo pulse voltage of only 3.3v. some servos are right on the edge of being able to detect this and read it correctly as they are expecting a pulse as big as the battery volts. I wonder if, in this case, the extensions are attenuating the pulse just that little bit? If you Google "servo signal booster", you'll see that there are solutions, therefore it is known as sometimes an issue. Having said that, it's probably as cheap to buy servos that are less fussy.
  4. Chris Bott - Moderator
    Andy, if it is that one, there's a huge amount of info in this forum area
  5. Chris Bott - Moderator
    Posted by EvilC57 on 22/07/2020 16:36:29: Posted by Steve J on 22/07/2020 10:19:40: If I am reading EvilC57's posts correctly, the title of this topic is misleading. The AR620 is not losing bind. It is losing a low power signal and not reacquiring it. Posted by EvilC57 on 22/07/2020 Yes, you are right Steve J, the receiver is not losing bind, it's losing the link - hence the reason it re-establishes OK on a power cycle (which obviously it wouldn't do if it had lost bind); I guess I was a bit misled by the bind light going out. I would rename the thread to reflect this, however I don't believe I can now - unless someone knows better . Thread title changed, EvilC57 - hope this s is OK now?
  6. Chris Bott - Moderator
    Good to see you again Vecchio. That's a very handsome Tucano you've built.
  7. Chris Bott - Moderator
    I've had a couple of questions sent to me about where to start with Arduino programming. To paraphrase, they go a bit like this:- "I'm happy building other peoples projects, using the IDE, compiling and uploading sketches, but I've no idea where to start with writing something of my own. How did you get started?" Now, I did indeed find it quite impenetrable to start with, and I know I have hardly scratched the surface yet, and have had some very welcome help here on this forum. So, how did you start? What would you suggest to a beginner? Are there any recommended guides or tutorials that quickly take the reader through the basic structure, using comments, void setup/void loop, ending lines with semi-colons and all those things that will trip them up before they've even started etc etc. Then, where is the best place to go to learn about programming, it's self? Any thoughts would be very welcome, I'm sure.
  8. Chris Bott - Moderator
    I'm sure I replied here yesterday thanking you both for your answers. It's clearly that age thing again. So, many thanks for the clarity. That's what's needed from FrSky.
  9. Chris Bott - Moderator
    Hi Dennis, I have to leave the house in 5 mins do this is off the top of my head. I (think I) have it saving all 3 readings when power is at a max. I did try recording all 3 independently, when they hit max or min. But often found apoarent anomalies between the saved max watts and the multiplied max amps and min volts. Would this explain what you're seeing? For the intended application, I think saving all 3 with a single trigger makes sense? What do you think?
  10. Chris Bott - Moderator
    It's mostly great gear at excellent prices but FrSky don't do themselves any favours with "support" like this, do they? Is there a version with and one without V tail? Could they possibly just be talking about quick mode and the full mode?
  11. Chris Bott - Moderator
    I'm sorry Richard but that's incorrect again. As soon as the ESC is connected, ALL cells see the same DISCHARGE current which is in the opposite direction to a charge current so all will start going down. While I agree that most lipos will stay in balance for a number of unbalanced charges and some will for many charges, any that are out of balance are likely to have that imbalance become slightly greater at each charge cycle. This is why balance charging was invented in the first place. Early lipos had no balance lead, early chargers had no balance facility and people had fires! I've heard folk complain that balance charging takes too long. Well, if that happens, it's telling you that your packs are being pushed out of balance by your charge cycles. I balance charge every time. It keeps my packs in balance. Very little time is spent in the balance part of the charge so my charges take only as an unbalanced charge. For anyone to suggest that balance charging is unsafe and that it's safer to charge without balancing (because of one event that was in effect a fault situation) really is dangerous talk and is doing a disservice to beginners reading this forum. Of course anyone can make their own choices. But balance leads are there for a reason and I will always use them. I also charge in a safe place and carefully monitor my charges too and I use a separate device to check voltages before and after charges and flights.
  12. Chris Bott - Moderator
    If I remember correctly a 3 axis gyro has 3 attitude sensors which will tell the unit which way up it is. But these are slow to respond to the slight changes that we need our gyros to correct. So 3 accelerometers were added hence the term 6 axis.
  13. Chris Bott - Moderator
    If the cells are in series, the charge current through each cell will be precisely the same. Without balancing, the charger will only know the pack voltage. So it will limit the pack volts of e.g. a 4S to 16.8V. But if 3 cells are only at 4V when one is at 4.2V the pack voltage will be 16.2V and the charger will keep pushing current in to get volts up. By the time it gets to 16.8V they might be at 4.15, 4.15, 4.15, 4.35 - an unbalanced charge causing overcharge of one cell.  Edited By Chris Bott - Moderator on 08/07/2020 20:40:25
  14. Chris Bott - Moderator
    I agree with Tim and think that charging without balancing has more potential to overcharge a single cell than balance charging. So I'll continue to balance, every charge.
  15. Chris Bott - Moderator
    I don't understand Andy48. If it was reading over 4.3 on the charger screen then it knew it was going past 4.2 and shouldn't have charged it further. If a bad connection meant that the reading in the charger was actually 4.2 when the battery was over 4.3 then you'd have seen 4.2. I'm missing something, aren't I?
  16. Chris Bott - Moderator
    Posted by Phil Green on 08/07/2020 10:44:44: I'd go further than that LHF, I would have hoped that on a public forum, mods would remove dangerous advice. I'd suggest that this is similar to the club arena where "everyone is a safety officer". If you see something that's unsafe you say or do something about it. That's exactly what's happened here. Well Wefore any of us mods looked in. My take, BTW is that I balance every charge to make sure no cell goes over 4.2V. if I watch cell voltages on my charger, balance charging a poor battery, as soon as any cell starts to go over 4.2v it appears to be clamped at 4.2 by the discharger being applied to that cell and the overall charge current is reduced to a level where that load can cope. I wonder if some chargers are better than others at accurately measuring cell volts. I think it's likely that each tapping point is measured from the 0v connection and some maths done to calculate individual voltages. I also agree that as current is reduced then connection resistance would have less and less of an effect and the over volts should be spotted. If I saw issues like this I'd be suspicious of either my charger or whatever device I'm checking with afterwards.
  17. Chris Bott - Moderator
    Eric can you get your video onto YouTube? Either on your own YouTube account or through someone else who has one? You need it there to be able to post it here.
  18. Chris Bott - Moderator
    OK that's fairly typical of OpenTx, when a short press will take you one way through a group of pages and a long press will take you back through them.
  19. Chris Bott - Moderator
    As Matty says, on OpenTx screens there are a number of "home" pages, you just need to find which is PgUp or PgDn buttons to scroll through them.
  20. Chris Bott - Moderator
    Posted by David Wilkinson on 27/06/2020 13:29:28: Hi Chris, Seems like I'm very late to the party. Just started with Arduinos a few weeks ago, and am building a vario sensor based on the OpenXSensor page. Do you have any of the PCB boards left? Don't worry if not. Was there anything in the magazine article that you've not covered here. I've tried to get hold of a back issue, but there doens't seem to be any available. Many thanks. David Hi David Yes I'm sure I have PCBs still. Certainly the fully functioning but incorrectly printed ones. Almost certainly some correct ones too. If I can dig out the mag I could photocopy the article and include that as well.
  21. Chris Bott - Moderator
    Whilst I agree that an IC engine is not dangerous while it's not running, and that it only takes the combination of a couple of mistakes for an electric motor to start unexpectedly, that's surely not the end of the debate. IC prop strikes dominate, in my experience, and that's because engine adjustments or removing the glow clip can require you to put your fingers perilously close to the prop. A moment's lapse in concentration can see you reaching through the prop too. I've even seen a loose tether cause someone to put their hand out to stop the model as it took up the slack and travelled towards him when he'd just started it.
  22. Chris Bott - Moderator
    Posted by Geoff S on 14/06/2020 22:00:26: Just setting up to use my Neuron 80 in anger. The motor I'm using is an old one and doesn't seem to be drawing as much current (and hence power) as my records indicate it did when tested it several years ago. I wondered if perhaps the throttle calibration is out and I've connected to BLheli32 to see. Minimum throttle is set to 1040 and seems to be OK (ie the motor stops when I shut the throttle) but maximum is at 1960 (presumably milliseconds pulse width) whih is less than the usual 2 mS. Just wondered what settings others have used as I think I may not be getting full throttle. Geoff Geoff if your Tx is going to 2mS then it's going past 1960 (uS), so should be producing max power just before the stick gets to the top, anyway.
  23. Chris Bott - Moderator
  24. Chris Bott - Moderator
    Here's a typical 6 minute flight on 6S, using 1357mAh. Peak power read 1121W
  25. Chris Bott - Moderator

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