Whisky, I'll swap your esc's for two surplus esc's I have here if you can wait till you get a packet next Wednesday.They've run 700BB turbo motors (PM me with your addy if you want to take me up on it)
Wom, I asked Whisky to use a bulb in case current trip was below 700 stall.....no joy.
PMK,Bluebird
Wom is spot on but try 2k2 to save a couple of milliamps.
As with all high gain inputs there needs to be an RF block so there is about 1 nF shunted from collector to ground
within the esc.
It's the
risetime that's too slow,transistor gain makes no difference. PMK's adapter should really put 1nf at input.
Thanks PMK for the description of pos neg shift but I see now that you your confusing it with polarity of the servo pulse train.I wasn't sure what you were getting at.
On the voltages...
the Futaba servo standard has always been TTL (2.2 on 5volt rail with light load) and receivers only increased to 2.5 because Futaba,using new 4000 series CMOS (rail-rail) in their receivers with a low drop 2.5 low drop reg. supply and then through a 270 ohm resistor.Some receivers did put out higher Rail-Rail pulses(Fleet,Acoms,bec) but that was incidental and never a standard.
That is where Bluebird's ESC designer c****d and up and nearly caved in under the deluge. Only just worked on 5 volt BEC and no more.
It's nowt to do with PCM sets....... it's down to CMOS threshold within the decoder that was assigned as an input pin (minimum 2.5 volt input at 5 supply)
Their first esc's used,an old servo chip, ZN409 could handle TTL levels but when the big changeover happened....oops.
Incidentally the early 10 and 15 amp models had two serious
"issues" when operated on anything other than 5 volt BEC. Their ZN409 had an inbuilt voltage dependency to stretch throttle which compensated for low battery in early servos and maintained arm movement speed.
When used in ESC's ,Futaba,Fleet,Hunter neutralised that tendency,as per the ZN409 data application recommendation. Early ZN409 E********ze and A****n ESC's didn't which meant that when the receiver pack went low the ESC noticeably went full out at only midrange throttle. Throttle setting had to be changed if batteries switched between NI-Cd and alkaline and E********ze could barely reach full throttle with four new alkaline batteries and the ESC throttle trim maxed out.
Another "small issue" in the last two types was the FET transistors were not fully switched on at low battery values.Consequently drive transistor resistance crept up and overheated,usually melting the two pole relay until the contacts shorted out the supply battery.
Fleet,Hunter designed out that possibility by charge pumping the FET gate voltage and Futaba used bipolar drive.Other manufacturers used low-threshold gate drive FET transistors.
Bluebird confirmed to me.(thanks
) that ihis esc was yet another voltage design
"issue" because I almost half believed the PCM story. If the supply voltage to the ESC is lowered to 5.0 it should work because that lowers the ESC CMOS input to just accept 2.5 volt servo pulses from mini receiver. Same reason why Acoms and Fleet servos will work with Futaba using re chargeargable (1.35 volt ) and not four 1.6 volt alkaline batteries.
Is receiver putting out 2.5 Bluebird? Did I read you had access to a scope? If receiver pulses are lower the 5.0 bec fix wont work for that Rx.
I initially thought the problem was down to the increased frame rates some PCM users told me. Some PWM receivers grab that reading to enable PCM like error correction.
DickD,did you read all of that
I just skip over long posts.