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[Obsolete] Low-pass filter schematic (old version)
#31
I'm using Aurel sender and receiver too - works fine, but 30m range? Never... it has problems to send through 2 walls and after that there is no chance to switch something- evene connected to this antenna: http://www.conrad.de/ce/de/product/19003...archDetail
 
#32
All my tests still point to the (correct) Ebay receiver as the superior ones. In price, functionality and range.
 
#33
Is there anyone with a picture of the connected LPF? I'm looking for a more efficient way to connect with less jumper cables.
 
#34
There is not really an efficient way because you need to connect nearly all schmitt trigger pins.
 
#35
See this bad picture of my pi and pilight and the LPF on a pcb:

http://i42.tinypic.com/2ch6fz9.jpg

Don't think you can do something with it, but it's a picture you asked about Wink

*EDIT: now in english, sorry CurlyMo, just thinking too dutch even when reading english
 
#36
English please!
 
#37
i think a redesign of the lpf isn't a to bad idea. i don't know where you got the design from, but are you aware of that you're using an opa circuit for bipolar (+5V/-5V) biassing?

imo the cut-off bandwidth should be at about 20KHz (as the lowest pulse length seems to be around 200us (http://www.sweetpi.de/blog/329/ein-ueber...protokolle))

a good guide for unipolar opa circuits is the following pdf:
http://www.repeater-builder.com/tech-inf...rcuits.pdf

using the circuit depicted in fig. 2 for biassing and the lower one in fig. 13 (so that the dual opv can be powered with 5V) i build an lpf and id works good.

btw. i'm using an aurel receiver with a self made antenna and get a indoors coverage of about 40m.
 
#38
Quote:i think a redesign of the lpf isn't a to bad idea. i don't know where you got the design from, but are you aware of that you're using an opa circuit for bipolar (+5V/-5V) biassing?
I made it myself with just very basic knowledge of electronics. I can solder and experiment, but that's it. So, still waiting for those real engineers to improve it.

Quote:imo the cut-off bandwidth should be at about 20KHz (as the lowest pulse length seems to be around 200us (http://www.sweetpi.de/blog/329/ein-ueber...otokolle))
The lowest pulse is around 100us with a medium of 131 in case of impuls. That's why it's so hard to receive. The lowest impuls pulses look very similar to the noise generated by the receiver.

Quote:a good guide for unipolar opa circuits is the following pdf:
http://www.repeater-builder.com/tech-inf...rcuits.pdf
I have no idea what the difference between a bipolar and a unipolar opa is Smile

Quote:using the circuit depicted in fig. 2 for biassing and the lower one in fig. 13 (so that the dual opv can be powered with 5V) i build an lpf and id works good.
Can you post the exact circuit you're using?
 
#39
i'm one of those electronic engineering guys ;-). the circuit i made is a lpf designed for a 3dB Bandwidth of ca. 20 kHz (=50us period length). it works good but i'm sure it could be improved (the problem is that a lpf is not enough because it's gonna stay at vcc/2 when noise is received and thus constantly switch the trigger). i think a bandpass would do a better job.

i'm gonna make a drawing of the circuit as soon as i found a good solution.

opa = operational amplifier
unipolar= biassed with i.e. +5V and GND
bipolar= biassed with i.e. +5V and -5V
 
#40
I can't wait Big Grin
 
  


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