RX voltage protection???

[Made2Fade]

Will this work guys and how?
http://cgi.ebay.co.uk/Reveiver-Volta...742.m153.l1262
Lee

[pchristy]

I sincerely doubt it! It looks like its just a 4700uF capacitor. To be effective, it would also need a resistor associated with it, but that would stop the servos working....!

All receivers have a resistor (typically about 100 ohms) in series with the power supply, and a capacitor in parallel. This is wired internally in the receiver and bypasses the supply to the servos which goes direct to the battery.

A capacitor and a resistor form a "time-constant" - a sort of reservoir that will iron out momentary voltage drops. Without the resistor, the time constant is in effect zero!

To be effective, you would have to open up the receiver and connect the capacitor across the receiver power rails AFTER the dropper resistor. Doing it across the servo plugs is futile!

--
Pete

[Randall]

In theory yes it works but just a small battery in effect. when you put a high load on say 3 servos the current can be quite high and some times the voltage can drop because of 1) the battery voltage drops under load 2) the resistance in the cable causes the voltage to drop all this will do is supply the nominal voltage in the pack for a brief second so if the battery voltage is 5 volts and you draw say 6 amps in a burst the voltage may drop to 3.8 volts for half a second the cap will just supply the 5 volts for a for that short period of time. thats the theory any way weather or not it works or not in this situation i do not know but in theory if you are getting lock outs etc then yes it would help

[Randall]

but yes the time frame would be very small with that size cap it would not cause you any problems appart from if the cap went wrong then you could be in a spot of trouble

[Made2Fade]

I used to have one of these caps on a micro rs4 electric car which i owned. If i remember correctly It was soldered inbetween the ESC and motor. It gave the ESC a small amount of punch from the instant the trigger was pressed instead of an increasing power effect. Made for faster or instant starts on the Car. Just wondered what this would do in a heli thats all.
Lee

[moyesboy]

Spektrum marketed this as an add on for their ground based systems when they fond that static disharge with cars runing on carpet could get the reciever to reset due to the disturbance to the power input.
People jumped on it as a possible way to hold the volts up on the helis but it will only provide a very short duration protection. The DCUP has a capacitance of 5 farads or something like that. Like plugging 1000 of these in!

Plugging it into a spare channel will smooth out any supply voltage peaks, and soften the effect of the stop/start/reverse momentary current draw from the servos. You may even see an effect of more crisp collective punch with CCPM when the 3 servos work together. But if the BEC cannot supply the total servo current demand, it won't save you.

On my raptor and 600n I have a 4700 uF cap across the servo supply. This is just to help the short term stop start and reverse current demand of the digital servos. I doubt it actually helps all that much, but it might give the 2 in 1 regulator an easier time of it.

The power to my rx comes direct from the 2 cell lipo at 7.4-8.4 volts (the rx is good for 9v). I don't think I'm going to see the lipo drop below 4v due to demand from the regulator.

[Andy from Sandy]

Based on what pchristy has written it brings into question whether the DCUP device actually does work as well.

[jsplace]

Has anyone got a fried AR6100 or 6200? I am currently working on a modification on the AR6300 nanolite to be able to run from a 1S LiPo. The mod will allow the reciever to operate anywhere from 2.5 to 9v with no reset at the usual 3.5v. Have got it sussed for the 6300 but need the others as I am not sure yet whether they use the same regulator as the 63.

[xygax]

Posibly if its configured corectly with an intergrator circuit. However firstly you will need to manufacture a set of connectors that the servos plug into to isolate the +ve feed to the servos. then use a schotty diode to feed the rx from this new servo bus. the diode type is critical and needs to have a foward voltage as low as posible <300mV then a bulk capacitor across teh rx will provide 'ride through' as the consumption of an RX is relitivly low compaired to servos a capacitor (low impedance low loss type) or a super cap 3.3 mF will provide a couple of seconds but they are a bit more expensive than a stanrard 40p electrolitic from fleabay....

The key is to isolate the rx from the servos using a diode then it will provide some protection.

Steve...