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Band-pass filter parts
#41
OK. Length of the antenna is clear (17,3 mm) but does the diameter matter?
I read it should be thin, that's clear. But how thin?
0,25mm^2 or 0,5mm^2 or 0,75mm^2?

Money is on the way.
 
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#42
We have a nice antenna thread with all info.
 
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#43
Hi Curlymo,

thanks for sending the filter+sender receiver so quickly. I did some tests today but was not very successful unfortunately.

I made the connections as they should be according to the wiring scheme (but only limit to 5V, ground and data pins, I did not attach the other pins for the Attiny (as I understand these are only required when you want to update the firmware).

I have installed xbian on a raspberry pi B+, and installed pilight according to the instructions (last stable version). When I start it without the kit attached everything runs fine, but when I start pilight with the kit attached the CPU load becomes too high, causing pilight-daemon to quit. This is caused by the GPIO thread which maxes the CPU.

Can you please give me some pointers on how to debug? I already checked the 5V and ground with a multimeter, these are OK so pin order should be good. I also did not include an antenna, but I don't suppose that could be the cause of this problem.

Thanks in advance for your help!
 
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#44
The cause is 99.9% of the time wrong connections.
 
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#45
Proper Ground and +5V supply
Wire all GND and +5V in star configuration to your power supply (for receiver, transmitter and LPF).
Proper 5V supply:
Use Ceramic condensators (100nF) as close as possible and with wires as short as possible at the chips (between + and GND)
Use at least one 4.7µF tantal condensator on each board (between + and GND).
 
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#46
OK, so I checked again with a fresh mind this morning but I still cannot see any faults in the wiring.
I have however bypassed the attiny now to make things a bit easier to debug, so directly wiring the data pin of the receiver to the correct GPIO pin (I of course removed the attiny from its socket). I get exactly the same error though.
Since the receiver only requires 5V, GND and data I do not really see what could be wrong. I have tried another (1.5A) adaptor.

I don't really understand wo_rasp's answer: GND and +5V are connected in a star configuration, but I do not have the 100nF condensator. It should work without the condensator right?

Or could it be that directly soldering the receiver to the board was not a good idea and that I fried the circuits? (although I tried to be careful)

Thanks for your help!
 
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#47
Yes, soldering the receiver could have wrecked things. Happened to me before. If the receiver doesn't work directly then clearly something is wrong in either your wiring or the receiver is wrecked.
 
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#48
(10-12-2014, 10:27 AM)gijss Wrote: I don't really understand wo_rasp's answer: GND and +5V are connected in a star configuration, but I do not have the 100nF condensator. It should work without the condensator right?
We have devices operating at 400MHz and above. Digital logic creates nS spikes on both lines: the 5V and on the GND wire. Those spikes can irritate other logic modules.
In order to block those spikes I recommend to add 100nF condensators directly between the GND/+5V pins of the devices and run separate wires from there to the power supply.
As you run all wires to one central point of your power supply, that kind of wiring is called star configuration.
At that central point of your power supply, i would add a 4.7µF Tantal and a 100nF ceramic condensator.
 
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#49
Can you create a schematic of it. For most users the filter itself is already some pretty advanced stuff Smile
 
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#50
Code:
+5V O----+--------+----O--------------------------------------o +5V
         |        |    O---------------------------o +5V      | Rx
         |        |    O---------------o +5V       | Tx       |
         |        |    O--o +5V        | LPF       |          |
   4,7µF |  100nF |         Pi   100nF |     100nF |    100nF |
       =====    =====                =====       =====      =====
         |        |         Pi         |           |          |
         |        |    O--o GND        | LPF       |          |
         |        |    O---------------o GND       | Tx       |
         |        |    O---------------------------o GND      | Rx
GND O----+--------+----O--------------------------------------o GND
 
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