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Old Apr 01, 2007, 11:37 AM
Kenny Fong is offline
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Build Log

DIY RC servo tester


RX output servo signal is 50Hz PWM,
with the high voltage width of 1ms to 2ms,
represents the travel of servo.

Use a high frequency timer and some program logic,
it's easy to make the high voltage width pump in the range of 1ms to 2ms,
thus build a so-called "servo tester",
like some TX function(FF9 has this), and some individual manufactures.

RC Servo Tester Board (0 min 34 sec)
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Old Apr 01, 2007, 11:54 AM
Acetronics is offline
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Hi, Kenny

30 years ago, we did that with a 555 driven by a 324 sawtooth generator ... Still have my proto in the cellar ... that showed moreover when current was more than .75A ...

Want the scheme ??? ...

Today, We have Gary's servo cycler beetween others.

Now, You just are the 1,268,683 th person that has designed a servo tester : congratulations ... you win the 1st of April Prize : The right to be known !!!

Keep on ...

Alain
Old Apr 01, 2007, 12:18 PM
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LOL - Alain you have a fantastic sense of humor

Kenny,
There is an old saying... been there, done that and have the tee shirt !
Oh and the board is huge ! - even using a NE555 and some desctrete components you should be able to fit it on a 1" square PCB !


Also with PIC micro's there are even more options - Gary's servo cycler shown above employs this technology - and all for just $20 !
Old Apr 01, 2007, 07:35 PM
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Yeah, cute.
$20 is not acceptable for this little device.
here in China $1 is enough.
and I prefer to use AVR, rather than pic MCU.
In fact the board shown in that clip is a general test board,
I use Mega8, and this application just uses its one port out, nothing else.
Old Apr 01, 2007, 07:39 PM
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Here is the C code block for cycling the width-varied PWM to servo.
Use MCU to accomplish this is almost a pure software work.

================================================== ============
unsigned int nStep=128;
unsigned int nCounter=0;
unsigned char cDirection = 1;

// Timer 0 overflow interrupt service routine
interrupt [TIM0_OVF] void timer0_ovf_isr(void)
{
// Reinitialize Timer 0 value
TCNT0=0xC3;
// Place your code here

nCounter ++;


if (nCounter >2560)
{
nCounter = 0;
{
if (cDirection)
{
nStep ++;
if (nStep>256)
cDirection = 0;
}
else
{
nStep--;
if (nStep<128)
cDirection=1;
}
}
}

if (nCounter < nStep)
PORTC.4 = 1;
else
PORTC.4 = 0;

}
Old Apr 01, 2007, 08:22 PM
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Quote:
Originally Posted by Kenny Fong
Yeah, cute.
$20 is not acceptable for this little device.
here in China $1 is enough.
One billion Chinese citizens can't even afford the luxury of a $1 servo driver, not to mention a robot/plane to put it in. Over there it's government subsidized labor at slave wages. When you send it here we call it dumping. I will support a US manufactured product without a blink of the eye, even at 20 times the so-called fair Chinese price. $20 is a fair value and affordable price here.
Old Apr 02, 2007, 03:36 PM
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deleted
Last edited by Gary Warner; Apr 02, 2007 at 03:59 PM.
Old Apr 02, 2007, 03:41 PM
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deleted original...

By re-reading the post, I had misunderstood the original author of the thread. The responses made it sound like a commercial venture - it's not.

To our friend in China, I DO understand that a DIY project makes much more sense than forking out $20US for a cycler. Here in the States we have this "time is money" mentality, so products like my cycler find favor with many RC people.

I do take a bit of an off-handed attitude to the comments about it being of less than top-notch quality. BTW, the raw PCB is made in China and it's tops in quality.

If you want to make your cycler more functional, take a look at what I did for features, both in software and hardware at York Electronics

Sorry for deleting my two prior responses, but I'm in a bad mood today and your comments didn't set well. I should think a bit more before posting.

Gary
--
Last edited by Gary Warner; Apr 02, 2007 at 04:09 PM.
Old Apr 02, 2007, 05:27 PM
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It's possible that I also misunderstood the posting also. $1.00 for parts is acceptable, even by US standards, but it gets under my skin that the labor and effort we put into the design and manufacture here in the US has to sustain us at some level. When the cost of labor in another country, like China, is so low that workers can barely feed themselves after working long hours, and that becomes the new standard for which we design and manufacture products....then we're all in trouble here. Let them raise the living standards of their factory workers and then there will be better equanimity in price and value.

You can't tell that I have a problem with our US trade policies ...eh?
Old Apr 02, 2007, 07:13 PM
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Quote:
Originally Posted by xorcise
It's possible that I also misunderstood the posting also. $1.00 for parts is acceptable, even by US standards...
Glad to see you add your post too. By looking at his video(s) on You Tube I get the idea he 'could' afford a $20 cycler, but he's more interested in the DIY aspect. From the looks of it, he may well have more cost in parts than I do with mine. One of most demanding parts in deciding weather or not to take mine public was the cost of parts. As it is, I have 58 cents in the PCB's and a total out-the-door cost of under $3 including packaging. Networking and finding parts cheap was no small feat.

I guess if I have a problem with China it's about the 'stealing' of items sent to them for manufacture and return. It's bad enough when it's done to our small industry, but when they do it on large military contracts costing us millions (or more) I get upset. It was in the news last week that we had night vision technology stolen from us by a China manufacturer. Now we have to redesign the technology from scratch as is should never have gone overseas for manufacture. Stupid move on our part, but still we have to pay the cost due to a very porous manufacturing environment in China.
Old Apr 02, 2007, 08:29 PM
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When competitive ideas and technology are protected within our borders, and we have assurances that our laws will protect us from foreign and domestic infringement, then we all benefit. It produces good jobs at home and provides incentive for smart minds and energetic bodies. A service economy is no economy. We need our engineering and manufacturing base back here and further protected by good trade laws.
Old Apr 03, 2007, 06:45 AM
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i see some sensitive teeth here. i think i did not have any intention to offend.
disappointed about that..
this is not a pure tech. sharing place I ever thought about.
most americans are moderate and helpful,
but obviously the rest few is always biting.
Old Apr 03, 2007, 08:26 AM
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I think I originally misunderstood your comments and took them as a scoff of US costs and labor values. For that I apologize.

I've ranted enough....don't take it personally. It's our own trade laws that have screwed things up here, and for that I do not apologize for my ire.
Old Apr 03, 2007, 08:47 AM
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Quote:
Originally Posted by Gary Warner
It's bad enough when it's done to our small industry, but when they do it on large military contracts costing us millions (or more) I get upset. It was in the news last week that we had night vision technology stolen from us by a China manufacturer.
It was sold to them illegally, not stolen.

There's a difference.

Andy
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Old Apr 03, 2007, 10:19 AM
Acetronics is offline
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Quote:
Originally Posted by Kenny Fong
i see some sensitive teeth here. i think i did not have any intention to offend.
disappointed about that..
this is not a pure tech. sharing place I ever thought about.
most americans are moderate and helpful,
but obviously the rest few is always biting.
Hi, Kenny ...

I just and only raised up you had re-invented the computerized wheel ... ( you take a square wheel, add another at 45 angle, another at 22.5 , alternating side from the root one....etc, etc, infinite times , and finally get the round wheel - )

Alain


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