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>> Home > Tags > capacitor

capacitor
capacitor
All hooked up, nowt happens... by jbkiwi Commander   Posted: 26 days ago
Hi Steve, I have the same problem with the ESCs in my HSL. They are cheap Chinese car models and can be a bit tricky to get into reverse quickly. I have found that either waiting a few seconds in neutral before trying reverse, or going to neutral and flicking the throttle forward a few clicks and back to neutral quickly (in .5 sec) usually sorts it. I think it may be that the motor stops somewhere that the cheaper ESCs can't detect (bit like an old car starter that hits the bald spot on the ring gear and you have to jog it a bit) so you have to move it slightly for it to 'see' it (maybe the capacitors also). Brushed ESCs don't have that problem as the brushes are in constant contact, rather than relying on correct positioning in Brushless motors. You will also find that some Chinese motors are not timed/wound correctly, and you can feel weak or 'floaty' spots between certain magnets which may also cause a problem. Perhaps trying a higher or lower ESC timing by 1 step either way might help if you have that capability. If it works by just flicking the throttle method, you can just slow down as you come in and take you time finding reverse in a scale like manner (remember the PT109 movie where they went through the shed on the wharf) You can also try swapping the other pairs of wires on the motor (same direction but different pairs). If you are still not happy then it might be time as Doug said, for a better ESC with instructions. Get one which has all the programing features, (fwd, rev , timing, auto batt detection (lipos or NmH etc) starting mode- ie soft,hard, brake etc) this will give you plenty of options for adjustment. Doesn't have to be a marine one, a good known brand car/buggy one will do and if you have any heat problems you can always put a mini fan on it. Water cooled marine ESCs are really only for high amp high speed setups. My 36"HSL has 2x 30A car ESCs running 2x 28/45 2000kv water cooled motors and ESCs never get even warm. Pictured are the ESCs I am using from HK which have an output plug for a fan if needs be. The 3rd pic is the brushed ESC types (EBay, AliExpress) I am using, which have no problems with reverse transition (see vid section re Thornycroft MTB maneuvering) also the HSL vids to give you an idea of how these brushless ESCs perform even with the minor reversing problem. Hope you get it sorted.

Internal wiring & bottom skins by ukengineman Petty Officer   Posted: 1 month ago
Hi Rob, the Police Launch is coming along nicely. I see that you have long leads from the battery to the ESC. The general rule is that these leads should be kept as short as possible to minimize voltage spikes caused by the fast switching currents and the inductance of the leads. Brushless ESC's have large capacitors, often visible at the end to absorb the transients. You may well get away with it but the life of the ESC could be reduced. Hope your Xmas goes well, Alan

HMS BRAVE BORDERER by RNinMunich Fleet Admiral!   Posted: 2 months ago
Hi Rowen, You don't need capacitors at all, and certainly not in series with the wiring. Whereas I can heartily endorse all that jbkiwi says about the possibilities of modern TXs, I've only scratched the surface of what my Spectrum and Turnigy sets can do, I can see no justification for the extra capacitors on ESC leads. The length of the wires inside a typical model can not have a significant effect on the total resistance. Given a typical resistance of 1m of copper wire with ca 1mm² cross sectional area of 0.02Ω (less for larger gauges) it ain't gonna make a happorth of difference whether you have 4" (10cm) or 40". Maybe a little more warmth but the capacitor can't change that. I also can't see where the spikes he mentions should come from. Also bear in mind that the ESC does not apply pure DC to the motor but a pulse train with a pulse repetition rate of around 8 to 10kHz. That's why the motors whistle and scream. Adding capacitors to this could distort the pulses or reduce their peak value. If the ESC is so bad that it produces big spikes when the pulses are switched on or off (which I doubt theses days) then junk it and buy a decent one. On no account fit a capacitor in series with the wiring, unless it is a special Coaxial Capacitor, which are very big and relatively expensive. See pic. I've only seen them on large electric motors on board ships where the much higher currents and longer cable runs involved than in models may play a role. A very small value capacitor, in the picofarad range might help to short out any potential high frequency RF interference but I've never experienced the need to fit them. In this respect it could be more important that the length of the cable is not close to the wavelengths typically used by RC sets (12.5cm at 2.4GHz) so that it does not act like an antenna. Cheers, Doug 😎 jbkiwi have looked at the link you posted but I'm not convinced considering the small lengths we use in our boats. Yes there will be some overshoot spikes in the pulse train but so severe as to damage anything is in my opinion highly unlikely, given a decent quality ESC in the first place. Something else on that link just occurred to me. There is a pic of what looks like electrolytic (polarised) capacitors between the wires. This is fine for aircraft ESCs which only run forwards, and thus produce positive going pulses. In our boats with reverse the pulse will switch over to negative going. Which after a while could have an explosive effect on the electrolytics. It blows the cans off and produces an interesting snowstorm effect. Good party trick😁 but maybe not so super inside a model boat😡 IF you do fit them to a reversible ESC be sure to use tantalum capacitors which aren't so fussy.

HMS BRAVE BORDERER by RHBaker Fleet Admiral!   Posted: 2 months ago
Doug, Am using the HobbyKing 50A Boat ESC 4A UBEC along with their programming card. The diode explanation makes sense so will fit one. jbkiwi My battery -ESC and ESC -motor wires are short, probably around 4" each. The addition of capacitors as suggested is intriguing as have never heard of it before. Think it is easier to keep things together in a boat, whereas with an aircraft pitch trim becomes a factor. Am using 2S batteries with a 50A ESC, with the motor max current of 30 A. Have you any idea what size of capacitor I should use? The Tx/Rx combinations are almost infinite as the ESCs are programmable too. Just wish the ice would go so can experiment! Thanks both for your help, with this hobby you never stop learning.

HMS BRAVE BORDERER by RNinMunich Fleet Admiral!   Posted: 2 months ago
Hi Rowen, Re Relays. The so called 'back emf' (reverse voltage) is caused when you switch off the relay. The magnetic field collapses and the energy is releases as a voltage spike with opposite polarity to the 'pull in' voltage. Since you are using an electronic switch this spike could damage the output transistor of the switch.😡 The diode is connected across the relay coil as a blocking diode, i.e. back to front wrt the operating voltage, and absorbs the spike. Each and any relay coil needs one! This is a manifestation of the induction effect which makes E-motors and generators work 😉 Capacitors: Parallel!! An idea with the Y lead👍 You'll lose the 'tank' steering assistance function though.😲 Happy experimenting, cheers, Doug 😎 PS I use the same alarms, also good for testing batteries on the bench, and ESCs from the same Quicrun range (in my Sea Scout for example), reliable and simple to set up. Even simpler if you buy the little programming card for them. Only a few bucks and well worth it. I've been wondering if it's the response of your ESCs which causes your 'modulation' problem! Remind me; which ESCs are you using? PPS have a look here for an explanation of the suppression (flyback) diode and how to connect it 😊 https://www.wikiwand.com/en/Flyback_diode

HMS BRAVE BORDERER by RHBaker Fleet Admiral!   Posted: 2 months ago
Thanks jbkiwi and RN in Munich for your suggestions: Have never used Ali Express, those components look interesting. Will follow up. I have used a battery alarm of the type suggested and it does work well. Have a couple for use once back on water. The rule about adding a capacitor into the ESC circuit is new to me. Have ferrite rings fitted so will now explore adding capacitors too. Are these is series or parallel with the wiring? The relays are not used with diodes or any electronic gubbins. Wanted to make the circuit as simple as possible for a Mechanical Engineer, so used one separate relay per ESC. The relay operation is controlled by a RC switch off another Rx channel. It seems to work. Am aware of the back feed possibilities and hope to have avoided them with the separate circuits. Appreciate any thoughts though, can add diodes if necessary. Am using a new FLYSKY 10 Ch. Tx/Rx on this model which opens up a host of programming opportunities. Am experimenting with various features such an the interval between Fwd/Rv also limiting ESC response. As am now using the brushless motors essentially in unison, also toying with controlling the 2 x ESCs on a “Y” lead on a single control. Much to think about, pity our winter has arrived early and the pond has been converted to a skating rink.

HMS BRAVE BORDERER by jbkiwi Commander   Posted: 2 months ago
Rowen, here are a couple of things that may be of use to you (and others). The battery alarm will save you worrying about running out of steam as they can be set to beep at varying voltages to warn you of low battery, just put one on each batt balance lead and when one goes off (when an individual cell drops below the set voltage) it means start heading back. These can be picked up on Ebay for a few dollars. I use them on my planes as well and are audable from around 100m (these twin horns are the best) Secondly, re your ESC switches, these electronic switches (AliExpress) are great for this sort of thing (as long as you have enough aux switches on TX ) You can link them with a Y cable to work together or use them independantly for anything, (lights, pumps etc, - they can be operated by TX rotary switches as well) The ESC and 2000kv motor (HK) are the ones I am using in my ASR model and will work smoothly down to a crawl, the purple 1980 kv seems to have superseded these but I think they will be as good. The props are from Ali Express and are resin and available in L and R hand, are only a few bucks and perform perfectly while looking quite scale(ish). I painted them with an acrylic bronze which seems to have stayed on pretty well. Model weighs 2.8kg and will run at more than 10mph flat out with this set-up (using the 26mm L+R) props) which is silly speed and that's with 2x 2s 2200mah lipos (which will last till you get sick of it and still have 60% left) I was just looking at your Daman set-up and noticed the wiring method from the batts to the ESCs. You might want to make your batt to ESC connections direct to your ESCs (as per original ESC lead length)as your capacitors may get a thrashing (spikes) due to the extra length/ resistance you have there. There is a general rule that you don't lengthen the batt to ESC wiring without adding a 220mf capacitor of same voltage as the ESC for every 4"of extra wire length (ESC to motor - not so much). Might want to check this out in case you fry your ESCs You probably have thought of this but thought I'd mention it, 'just in case' Might help with your modulation as well. Have chucked in a vid of the HSL manouvering (first trials so wasn't perfect) and also the MTB (brushed) which I have just converted to a twin system (was twin but single Electronize unit) plus a sound unit. You may know that you can use as many RECs (bound to the same TX) for various purposes on the same boat (have run 2 boats together from the same TX) Might get you round the mixed brushless/ brushed problem with a bit of thought. Have you thought of changing your old HK silver 6DF TX to twin throttles, it's a piece of cake(as is the TGY 6x), just remove the aileron/rudder centering spring and make a friction plate as per throttle stick, and use the elevator channel as your other throttle. Set your ESCs and you can then use a twin system giving you perfect control. Saves a lot of hassle.

All hooked up, nowt happens... by RNinMunich Fleet Admiral!   Posted: 2 months ago
You're as BAD as me Boaty 😉 but I had a Rover 2000 with fully reclining seats back then - no problem 😁 Re 3 wires on a brushless. Simply put, this is analogous to a 3 phase AC motor (such as used in bathroom extractor fans etc). If you apply a single phase AC voltage to an AC motor it just twitches backwards and forwards in the same place as the voltage crosses from the positive to the negative half cycle. Thus 3 phases are applied giving 3 'shoves' in sequence to keep things moving. A starter capacitor is also needed to give the motor a 'belt' to shove it off. Similarly with a brushless: the ESC senses where the motor armature is in relation to the magnet poles and applies a DC pulse to the next armature coil in sequence. When you shove the throttle up the pulse width lengthens applying a longer shove and thus more energy and speed. Pulling the throttle back with a reversible ESC just turns the pulse train upside down so that negative DC pulses are applied to the motor, reversing the magnetic field created in the armature and thus the rotation. Simple really. It's the sensing and timing done inside the ESC that's the tricky bit, which is why we had to wait about a hundred years from the invention of the AC motor (Nikolai Tesla) until we could use them in models - thanks to micro-electronics. Here endeth today's seminar 😁😁 Happy brushlessing Folks, cheers, Doug 😎 Hmmm, perhaps that's why electric toothbrushes use brushed motors! 😁😜

Taycol Supemarine Resurrection by RNinMunich Fleet Admiral!   Posted: 4 months ago
Hi Boaty, The Taycols have fascinated me as well, ever since I dug the Target out of the Sea Scout my Dad built in the early sixties. I blogged my renovation of that and the conversion to run with a modern RC system and presumably that, and the converter boards I built for Martin (Westquay), is what triggered Colin to ask me to have a look at his Supermarine. How could I resist!? 😉 The 'smell of something electrical' is the ozone gas caused by the prolific sparking of the Taycol metal to metal brush / commutator combination. The other source of Ozone is on the coast wherever there is a strong surf! I agree, a nostalgic smell, which unfortunately disappears when the converter board is attached to make it run with a standard brushed ESC. The diode bridge kills almost all the sparks. 'Almost' so the usual suppression capacitors are still recommended. 0.1µF across the brush terminals, 0.047µF from each terminal to the motor can, or frame in this case. Earth to prop shaft tube as well if possible. The motor may not disturb the on-board electronics of your own boat, if using 2.4Gig, but could still affect anyone nearby using 27 or 40Megs. The power density of spark transmitters (e.g. unsuppressed E-motors, peaks in the upper HF bands and diminishes to almost zilch in the UHF bands. I.e. approx 300 MHz upwards. Like me and other submariners for instance; 2.4Gig is useless for subs cos it don't go underwater. Cheers, Doug 😎 But here! BTW Boaty: where are the pics of your Avanti? Harbour posts without pics are pretty dead 🤔 Cheers, Doug 😎

Launch ELAINE, by onetenor Fleet Admiral!   Posted: 5 months ago
And what a capacitor. Big enough to have come from a washing machine of that period. Maybe it did. The whole thing looks like a lashup. Used whatever would work.I had loads of old valves but noone wanted them so dumped them. Some of them were More modern ones to replace the DCC90 but 1/3 or less the size. Those relays look like the old G.P.O. type. We got them from a Gov't surplus shop for buttons. Those were the days. Sometimes we added in an R.A.F r/f amplifier without the case. It increased the range but don't ask me now how we wired them in. There were 4 connection points on the casing which accepted a multi-plug connector secured by a threaded ring. Nice bit of kit til we got our hands on them.😁

Launch ELAINE, by RNinMunich Fleet Admiral!   Posted: 5 months ago
OK twigged it! The 'second' bottle is the end of the capacitor, still in the box.🤔 Ciao, Doug 😎

Launch ELAINE, by Colin H. Fleet Admiral!   Posted: 5 months ago
Appreciate your help, apparently only the large capacitor and 1 of the relays is suspect. The radio magicians from camp it would be possible to replace them but it would lose its value as an exhibition piece. Cheers Colin.

SLA Batteries! by RNinMunich Fleet Admiral!   Posted: 5 months ago
Mornin' Ed, Veery interestink! These PNP ESCs from mTronik are relativley new. I have some mTronik Viper Marine 10A for my smaller 'brushed' boats and on first use I simply have to teach them which way on the throttle stick is forwards and which backwards. Looking at the so called manual for your PNP version I note instructions and notes as in attached pics. How you re-train it I can't see! Maybe just start again from switch on, but watch what you do with the throttle stick. Also seems it 'adjusts' as you use it. Quite what that means they don't explain🤔 Give 'em a ring and ask! I guess you reckoned; 'OK PNP so who needs to look at the manual'! Common mistook!🤔 What do you mean by "I then have to switch it to go forward." Switch what, where and how? And what effect did it have? Cheers, Doug 😎 BTW: what's that right next to the motor with cables trailing over the motor, and why can't I see any suppressor capacitors on the motor?

Launch ELAINE, by Colin H. Fleet Admiral!   Posted: 5 months ago
Well today the radio specialist guys checked out the reciever for me, apparently it would need a new capacitor, a 90 volt and a 2 volt supply. Not really possible in such a small boat. So I've decided to use it for my vintage displays. The boat itself will be renovated and fitted with an electric motor, possibly a 600 as I have a couple in the spares box. Still looking for a way to remove the kitchen nozzle system. The motors that operate it are working so hopefully should be controllable by modern rc gear. Might need Dougs help designing a system I can build. BTW the Hull and cabins and deck is constructed from 1/4 Inc ply. Bit heavy but good and solid except for some of the frames are very soft and crumbly. Will start a resurrection blog soon. Cheers Colin.

Old Futaba servo wiring... by terrymiff Chief Petty Officer   Posted: 5 months ago
Hi Admiral RNinMunich sir, I was going down the route of building a 2.4GHz Detector/Meter until I came across this: https://www.banggood.com/Lantian-Mini-High-Sensitive-2_4G-Fr... It works a treat and for that price it is not worth running around getting parts for a diode/capacitor/meter circuit. Cheers from DownUnda