PCM receiver problems
12-24-2007, 08:12 AM
#1
Member
Thread Starter
Join Date: Jan 2007
Location: Doncaster, UNITED KINGDOM
Posts: 41
Likes: 0
Received 0 Likes
on
0 Posts
PCM receiver problems
Can anyone please answer why this is happening.
I have a firmtronics rc switch which basically supplies an output voltage from the receiver battery when switched this works great with my ppm receiver but not with my pcm receiver. If I put a servo on the output it works perfectly so there is no problem with the receiver. Im a little lost.
Switch details http://www.firmtronics.com/rc-products/rcswitch.php
The problem is I cant ask them as its the chrismas break and want answers asap.
I have a firmtronics rc switch which basically supplies an output voltage from the receiver battery when switched this works great with my ppm receiver but not with my pcm receiver. If I put a servo on the output it works perfectly so there is no problem with the receiver. Im a little lost.
Switch details http://www.firmtronics.com/rc-products/rcswitch.php
The problem is I cant ask them as its the chrismas break and want answers asap.
12-24-2007, 09:17 AM
#3
Senior Member
Join Date: Nov 2005
Location: Mount Royal,
NJ
Posts: 174
Likes: 0
Received 0 Likes
on
0 Posts
RE: PCM receiver problems
In the PCM mode, some recievers have a low signal voltage to the servo. Maybe half or a little bit more than in the PPM mode. Like 2 1/2 to 3 volts in PCM instead of 4.5v or higher for PPM.
The switch probably needs a higher voltage signal than the PCM in your reciever will give. If that is the case, the only answer is a signal buffer in line to the switch.
The best thing in my opinion is to wait and call them to see what their solution is.
Hopefully someone else will post that has had this problem with the product and found a simple solution.
The switch probably needs a higher voltage signal than the PCM in your reciever will give. If that is the case, the only answer is a signal buffer in line to the switch.
The best thing in my opinion is to wait and call them to see what their solution is.
Hopefully someone else will post that has had this problem with the product and found a simple solution.
12-24-2007, 09:38 AM
#5
Senior Member
Join Date: Nov 2005
Location: Mount Royal,
NJ
Posts: 174
Likes: 0
Received 0 Likes
on
0 Posts
RE: PCM receiver problems
Try this to see if it works.
IF you have been using a 4.8 v pack, try a 6 volt pack if you have one. The extra voltage might just be enough boost to the output of the reciever to trigger the switch. You might get another 1/3 to 1/2 volts on the output signal. At least this MIGHT let you know if it is the low voltage signal problem.
Looking at the manual posted on their site, the unit needs a signal of at least 2.7v to trigger the switch.
As a side note, hooking up a voltmeter to the signal wire to see what the voltage is will not give any meaningful results. you need a ocilloscope to see the signal pulses and their voltage.
IF you have been using a 4.8 v pack, try a 6 volt pack if you have one. The extra voltage might just be enough boost to the output of the reciever to trigger the switch. You might get another 1/3 to 1/2 volts on the output signal. At least this MIGHT let you know if it is the low voltage signal problem.
Looking at the manual posted on their site, the unit needs a signal of at least 2.7v to trigger the switch.
As a side note, hooking up a voltmeter to the signal wire to see what the voltage is will not give any meaningful results. you need a ocilloscope to see the signal pulses and their voltage.
01-07-2008, 10:35 AM
#6
Member
Thread Starter
Join Date: Jan 2007
Location: Doncaster, UNITED KINGDOM
Posts: 41
Likes: 0
Received 0 Likes
on
0 Posts
RE: PCM receiver problems
Thanks for everyone who tried to help. I have found the problem. On the suggestion from firmtronics I fitted an ossilloscope to find the refresh rate of the signal from the receivers. The ppm has a speed of 20ms where as the pcm has a speed of 14ms. The device looks for around 20ms and anything else is seen as noise and the device shuts down. They have said they will send me a new one free of charge with updated software. Thanks Firmtronics.
