Quote:
Originally Posted by Andrew32
i would like to invest in something like this. Had one blow years back and took out the servo....not the receiver strangely....
Brian, are you going to put this on a board with pwm leads coming off the ends for easy installation?
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My spektrum receiver has a voltage regulator built-in so the circuit was voltage protected, so I imagine other receivers will have something similar. But when the servo blew from the high voltage, it drew lots of current through the receiver ports which fried the traces connecting the power pins. I had to solder a bridge wire across those pins and it was fine. So, it was
over-voltage protected, but not
over-current protected.
Like I said previously; to keep assembly cost low, I may just do point-to-point wiring. But a small piece of perfboard shouldn't be too bad. And it will come with servo leads already installed.
Quote:
Originally Posted by whitrzac
mabey this is a dumb question, buy why couldnt you use a bar resistor to bring the voltage from the lipo down to power the RX strait from the batt??  or am I compleatly stupid??  |
Quote:
Originally Posted by J57ltr
A resistor would only limit current not voltage. Think of it this way if you have a hose and it has a restrictor placed in line with it very little water will come out the end limiting flow (amps), but if you plug the end the pressure (voltage) will rise to the same as before the restriction. So when the current draw is near 0 the voltage will rise to a dangerous level and take out the RX and servo.
Brian this would be easy to add to the existing BEC on the board. Good idea using the fuse, I figured that the trace would be good enough. 
Jeff |
Lile j57ltr said, a resistor wouldn't work well. If it was in series, all it would do is drop more voltage as the load increased. Maybe good for when the BEC goes bad, unless no current was being drawn and voltages rose, but would also have varying voltage drop for normal loads.
Yeah, using the trace as the "fuse" may work, but then there is a risk of fire of whatever. A purpose-built fuse controls where the failure will occur.
Quote:
Originally Posted by suicideneil
Dont they make shorter servo extension leads, sure I've seen massive lots for sale that are very short and cheap...
I like the circuit though, it really is so simple even I can understand it for a change  |
Yup, it's simple all right. If it works, I'm amazed that manufacturers haven't included it as part of their design. And I'm sure I can get bulk servo leads for less cost, but would most likely need to order something like 500-1000 to see the benefits. And even at $1 per lead, it gets expensive. Especially if interest is low. Total build cost would be under $3 per unit, but I'd have 1000 units sitting at home not being used.
I'll probably go ahead and order a few component sets just to do testing. If it works like I hope, will assemble around 20 kits and go from there.