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>> Home > Tags > capacitor

Old Futaba servo wiring... by terrymiff Petty Officer   Posted: 4 days ago
Hi Admiral RNinMunich sir, I was going down the route of building a 2.4GHz Detector/Meter until I came across this: 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

Range Safety Launch? by RNinMunich Fleet Admiral!   Posted: 13 days ago
Hi Neville, that far forward I would definitely look for some hull damage forward; crack in a seam or delamination? When you find it clean off all the paint around it, seal it with EzeKote and repaint. Inside fill either side of the keel in that bay with resin. Check also the skin joints around the chine. Re motors; I don't see any suppression capacitors 😲 and the motors (or the one I can see) are mounted very high giving a very steep shaft angle! Will tend to push the bow down at speed instead of planing🤔 Ciao, Doug 😎

Martin's Taycol Conversion Boards by RNinMunich Fleet Admiral!   Posted: 20 days ago
OK, In chronological order😉 No! The Wattmeter has to be spliced into the cable between source (i.e. battery) and the load, ESC and motor. As shown in example 1 in the instruction extract above. BTW 1: if your Wattmeter comes with instructions in Chinese Unwinese (Misstoodifold in the under number 29s😁) then use the above. Despite it's name it's primary use to us is to tell us the current the motor draws so we can select appropriate fuses. It will also tell you the mAh you've taken out of the battery, or put in when on charge. As far as I'm concerned the actual Watt measurement is relatively useless, except perhaps for 'Bragging Rights' 😁 Speccing the ESC should be done by checking the motor current specs and adding a good margin for safety. If no specs available use the Wattmeter to tell you the current drawn at full voltage from a DC source. If possible under load in the bath. Hang on tight😲 That only works for BRUSHED motors of course! Then use an ESC capable of twice the measured current. BTW 2; if you want to use your 27 / 40Mhz TXs you will definitely need the suppression capacitors on the motors, despite the partial damping effect of the rectifier, to reduce interference to your own radio. Fuses; I'll put 15s in to be on the safe side. If the Wattmeter / Ammeter measurements indicate less than 10A max then change fuses to10A and use a 20A ESC so it has some reserve. Or is operating within it's true capacity😉 Cheers, Doug 😎

Hull Pt2: Motorisation - Come What May!! by RNinMunich Fleet Admiral!   Posted: 1 month ago
As promised (or threatened?😁) stage two of the hull work and thoughts on motorisation. The hull was sprayed with two coats of grey primer/filler. Pic1. As usual this showed up the remaining imperfections (pics 2 & 3), but I'm not going to worry about them until I've got prop shaft tube and rudder stock sorted out and permanently fitted 😉 After my attempts to make and thread a 3mm prop shaft went awry Martin (Westway the Mechanicals Master👍) stepped in and made me a decent one complete with a bushed stuffing tube 👍 Vielen Dank Meister😊 I did however manage to make a 4mm to 3mm reducer so that I could fit a Rabeosch 35mm prop as seen in pics 2 & 3. The tube and shaft from Martin, arrived Saturday an' he only made it on Monday😊, have been dry fitted so that I can start setting up the gears, necessary to bring the drive down to the prop shaft fitted very low down in the hull, and motor mount. Pic 4. Motorisation: (Remember folks - this kit was designed and built as a static model!) I want to use the old 1950s Taycol Target motor which my Dad originally fitted in the Sea Scout which I have renovated and upgraded to brushless. See Build blog 'Sea Scout - Jessica' Many of you will know that the Taycol motors were field coil motors, meaning that they have no permanent magnet around the rotor coil, and thus reversing the battery connections to the brushes had no effect on the direction of rotation, as this simply reversed the magnetic fields of both stator and rotor coils🤔 To counteract this so that the motor could be used in both forward and reverse with a conventional brushed ESC I modified the motor slightly (separated the two coils) and built a simple converter board to connect it to the ESC. Again see the Sea Scout blog for the details of the conversion. Basically; once the field coil and brush-gear (rotor coil) have been separated a simple diode bridge can be used to apply the output of the ESC to the motor. This enables the reversal of EITHER field OR rotor coil polarity, depending on how you connect the converter to the motor. Thus reversing the direction of rotation of the motor. Beneficial side effect is that the diodes also suppress the commutator sparking😊 In my case, with the Taycol Target, I also cleaned, flattened and polished the commutator. Thus significantly reducing the potential for spark generation in the first place! A peculiarity of the Taycol motors is that they all use metal brushes, pressed phosphor bronze strip, so they need oiling! DO NOT oil conventional brushed motors with carbon brushes unless the brushes are exchangeable or you want to have to buy a new motor!!!!! Pics 5 & 6 show the proposed position of the Taycol in Gina 2 and pic 7 the prototype converter board I knocked up to test the motor, together with a Graupner Navy V30R Marine Brushed ESC. Details and results in the Sea Scout blog, including video of the sparks and oscilloscope pics of the drive waveforms before and after conversion! The latter showing the spark suppression effect of the converter😊 Some samples attached - last 3 pics. Pic 8 pic shows a more compact version of the converter, one of a few types I'm doing for Martin's various Taycols as a trade for the prop shaft he made for me and some useful material he sent. Thanks mate👍 Next steps will be 1) mounting the gears correctly on the shafts, requiring the manufacture of a 3/32" to 4mm adaptor and a 1/8" to 4mm adaptor, and keying them to the shafts - Hooray for mini milling machines 😉 2) manufacturing bushed end plates to hold the gears in place, 3) fitting the motor mounting platform. I'll probably borrow from my experiences of real shipbuilding and do this as a suspended 'false floor', i.e. mounted on stiff springs to enable adjustments to optimise the gearing mesh! On real naval ships this is done to improve shock resistance and to minimise engine noise / vibration conduction to the hull, thus significantly reducing the acoustic signature of the ship. Not that I'm tooo worried about being torpedoed 😁 Worth a try😉 Pic 9 shows the cleaned up and renovated Taycol Target motor. Pic 10 shows the drive waveform complete with sparks before modification.🤔 Pic 11 the cleaned 'forward' waveform with the converter board. Pic 12 the cleaned 'reverse' waveform, no suppression capacitors needed 😉 More soon folks, Cheers, Doug 😎 PS Along the way a new keel was fitted as can be seen in pics 1 to 3. The original builder had 'buried' the keel in the hull planking! 😲

Spektrum, new, useless... by RNinMunich Fleet Admiral!   Posted: 2 months ago
Hi Martin, You do like living dangerously don't you!? 😉 Why don't you ever buy anything from the same manufacturer to be sure it will work, or have the chance of regress if it don't! Anyway, since you've been an' gorn an' dunnit - Ignore the PPM, that just means Pulse Position Modulation. A type of TX modulation waveform that you don't need for the Spektrum TX. Forget the Stat as well. I suspect that that should be SAT for a Satellite RX. No that don't mean you can watch telly on it😉 It's just a connection for a secondary RX. Never ever seen one in action! The others are the usual aircraft / chopper functions in a particular TX Mode, so you can ignore the labels. We can use the channel outputs for whatever we want in a boat. Attached is a description of the binding I found in an RC flight forum. A little bit Chenglish but clear enough I think. Your Simprop 18A job should be more than man enough for your Supermarine. I don't expect that it will eat more than 10 or 12Amps. Put a 15A fuse in the + supply between motor and the mod board that makes it run ahead & astern; i.e. the + output of the bridge rectifier. That will protect the motor coil and brushes. Put another in the + from battery to ESC to protect the ESC and rectifier. Rectifier should be rated at least 20A peak forward current. 30A might be better in case your Supermarine is hungry! In that case use 20A fuses. 10A was enough for my little Target 😉 See attached pic for the mods to the Supermarine. Connections from the rectifier board to motor are- + and - of the rectifier go to the brush terminals. Of the two ~ (= AC) one goes the field coil. The other goes to the - wire from the ESC. + from the ESC goes to the other end of the field coil. If the motor runs wrong way (with respect to throttle stick) just reverse the brush wires as usual. Don't forget the suppression capacitors, you may not need 'em due to the spark suppression by the rectifier but ... JIC😉 Bon chance mon ami 👍 Cheers,Doug 😎

Spektrum, new, useless... by RNinMunich Fleet Admiral!   Posted: 2 months ago
Evenin' Martin. Don't smash it, although I can well understand the impulse! Send it to me, you know where I am. I like a challenge😉 I'll refund you the postage. Cheers, Doug 😎 PS: Martin, unfortunately there are some things that NEED use to keep them working! In electronics this means particularly the electrolytic capacitors, those marked + and - on the leads. Of which there will be several in the TX. Just switching it on now and again prevents deterioration of these components. If left alone for years they can go 'soft' and prevent whole circuits from working. Fact of electronic life I'm afarid.

Seeing the light by RNinMunich Fleet Admiral!   Posted: 2 months ago
Hi Peter, Glad it works at all! 😊 1. the capacitor on pin 5 has no effect on the timing circuit. It's only there to stabilise the 555 chip and stop it 'going off it's trolley' at higher frequencies 😉 It should be 10nano Farad, not micro Farad. It's job is to short any stray high frequencies to ground. 2. Attached is a table of results I would expect for the values you gave me, and various values of the pot R1. The duty cycle (%age On time) should vary between 50% and 95%. Max on time 1.4sec at R1 = 200K. But Off time of 32mSec you'll hardly notice.🤔 3. R2 is way too small at 4.7k compared to the 200k pot. I warned you that it needed to be similar to the pot to make the adjustment less sensitive. The low value is also the reason why the Off time (discharge time) is so short at 32.62mSec 😲 4. The timing cct is governed by R1, R2 and C. Pic 2 shows the output waveform switched between Vcc 6V and 0V- Increase C to increase the whole period (T1+T0) (reduce the frequency). Increase R1 to increase High Time (T1), without affecting the Low Time (T0). Increase R2 to increase High Time (T1), increase Low Time (T0) and decrease the duty cycle. 5. Your 180Ohm resistor is about right for an LED with 2.5V Forward voltage drop and 20mA current. If the LED actually wants 30mA you can go down to a120Ohm. So, how much is 'increase the on time a little'? What cycle frequency do you want? How long On and how long Off? Since you are 'Breadboarding' you could just try plugging in different fixed resistors for R1 (instead of the fiddly pot) and R2. Pic 3 shows results for R1 = 47k and R2 = 100k, C = 10uF. About 1Sec ON, 0.7Sec Off. Cheers, Doug 😎

Seeing the light by MouldBuilder Commander   Posted: 2 months ago
Evening Doug. I have made up a couple of circuits. They both work well. I have fitted the variable resistor to your design and it works really well. The circuit components are as follows. R1=200k variable. R2= 4k7 resistor. Chip= 7555 CMOS. Capacitor after R2=10uf. Capacitor at pin 5 = 10uf. Single blue LED is 20mA with a 180r resistor. Battery voltage 6V. I have some strange results. The variable resistor works well but strangely, if I disconnect the capacitor at pin five, there is no effect to the flashing light at all. It still works well. There is also no effect if I increase or decrease the value. I am happy with the results but would like to increase the on time a little. Please can you tell me which component should be altered and whether the value rises or falls. Thanks for your help.😉

Seeing the light by MouldBuilder Commander   Posted: 2 months ago
Hi Doug. It is a 1M pot. This is a single turn component. I also have 5k multi turn, 200k one turn, and 500k 1 turn. I have loads of resistors. 1,10 and 100uf capacitors.😊 The LED`s are 20mA. I have been reading the Tug lighting thread. Interesting. Thanks.

Seeing the light by MouldBuilder Commander   Posted: 2 months ago
Hi Doug. Still waiting for some components to arrive so that I can try this circuit on my breadboard. One question though. My trimmer pot has 3 contacts. I assume that the middle one is the wiper and the other two are the resistor. Do I connect pin 2, the middle one, to V+ and the other two in line to pin 7. Could you suggest values for R1 and R2. The capacitor in series with these, would 100uf be enough to start and if not enough, how many additional uf is required to make a difference. By the way, the chip is a 7555 CMOS. Thanks.🤓

Seeing the light by RNinMunich Fleet Admiral!   Posted: 2 months ago
Hi Peter, attached the pinout of the 555 and a circuit for an astable oscillator giving a square wave output suitable for a lamp flasher. Frequency (flash rate) is defined by R1, R2 and C. The bigger the 'C' and/or R1 the slower the rate. R2 defines the discharge rate. Therefore the ratio of R1 +R2 to R2 defines the ratio of On / Off times! A little experimentation needed. You can put your pot in place of R1 for some flash rate (F)adjustment. F=1/Cx(R1+2xR2). If you want to get really 'snazzy' you can use the 555 in monostable mode (pic 3) and use the pulse output from an RX channel as the trigger input. You may need to add a series capacitor and a resistor to ground (try a 10K to start with) to slow the trigger down a bit and experiment with the capacitor, a small electrolytic or Tantalum. It helps if you have an oscilloscope for such experiments! A cheap analogue 100Khz or 1Mhz job would do. The astable version is simpler, just put a remote controllably switch e.g. transistor switch board or, even simpler, just a microswitch mounted on a servo😉) in series with the Vcc (+ supply) to the timer chip. It takes longer for the first flash after switch on to occur as the cap has to charge up from 0V to 2/3 Vcc. After that only from 1/3 Vcc to 2/3. Ratio of ON time to OFF time depends on R1 and R2. ON=Cx(R1+R2), OFF=CxR2. Happy soldering and Flashing 😲, cheers, Doug 😎 PS: are your 555s bipolar or CMOS? Makes a difference! Bipolar types only drive the output to Vcc-1.7V. CMOS types drive the output to full Vcc😊 PPS: One other point! Is your 'Blue Lamp' a bulb or an LED? If an LED you will need a resistor in series with the output to limit the current to a max of about 30mA. Start with 1KOhm, if too dim go down to around 220/270Ohms.

Memorial Running by Novagsi0 Captain   Posted: 3 months ago
Last nights running on the anniversary of my Dads birthday, we started to boat together but it then sat on the shelf for over 30 years. Now finished by me and my mom, we sadly didn't finished it together dad. Forgot to mention adding the capacitor across the motor seemed to fix the RC problem last experienced.

More running in at Bournville. by Novagsi0 Captain   Posted: 3 months ago
Update from MFA Como The motors, as they are, sufficiently comply with CE regulations for electrical emissions. However, sometimes with radio control you may need the extra suppression to stop radio interference. Initially try one capacitor across the terminals, this is usually a 0.22uf.

More running in at Bournville. by Novagsi0 Captain   Posted: 3 months ago
The motor is only a few months old, bought new for Howe's models. I've heard of old radio caps going dry and I means after 40 years of service, since the brother in law repairs old radios and juke boxes. But not capacitors after 16 weeks, the motors only done 3 or 4 hours of service in total. I've added an additional cap across the terminals. I also had a reply from the speed controller company they said to check the fail safe on the transmitter which incidentally is working to kill the throttle channel as its a fly sky intended for a (plane).

More running in at Bournville. by BOATSHED Fleet Admiral!   Posted: 3 months ago
That's an odd thing to say. They don't last for ever,especially if they are not used. What about being stuck in shops or wharehouse's and not bought for years. They wouldn't be any good then when you buy them. Surely capacitors don't have a shelf life. I could understand them breaking down when constantly being used.