stripboard's capacitance between adjacent tracks and received signal - Electronic Circuits Projects Diagrams Free

micael · 28th July 2006, 12:47 AM

Hi

"Never place a Transmitter or Receiver directly into Vero-Board or any similar prototyping board. This will severely restrict the range. Rather, use small lengths of wire from the prototyping board to the pins of the Transmitter or Receiver."

The question is were to put the transmitter or receiver modules and their antenna??

Why the stripboard's capacitance between adjacent tracks affects so much(reduced) the received signal from 17.3 wire antenna placed on a striboard?

dknguyen · 28th July 2006, 12:57 AM

Your quote implies that the transmitter/receiver should be separated from the proto board by long wires- that's where it is telling you to put the transmitter/receivers and antenna- away from the vero board, it doesn't matter where exactly- I think that the inductance introduced by the wires is supposed to counteract the parasitic capacitances on the veroboard.

Radio circuits by their nature work with specific frequencies and parasitic inductances and capacitances (like those caused by all the generic traces on the proto-board cause problems. Imagine an R-C filter. Good right? Now imagine that instead of just plain old perfect ideal wires connecting the R and C, the wires connecting them are REAL wires. Real, really messy wires that loop all over the place and branch off and meet each other again (like all the unused traces on the vero-board). The lines that are wires in your circuit schematic aren't lines anymore, they are other capacitors and inductors. They essentially introduce extra capacitors and inductors and resistors into your circuit which will cause it to work differently. When your circuit is a radio circuit and has to be tuned precisely to work, these extra parasitic components cause problems. In the case of the R-C filter they will change the frequency that your filter will work at.

micael · 28th July 2006, 01:26 AM

I m using FM-RRFQ1-433 FM Receiver , SIL Package, 433MHz module which has to be mounted on a Vero-Board so...how i ll keep it away from the vero board????

audioguru · 28th July 2006, 01:31 AM

433MHz is darn high. Nearly microwaves. A couple cm of wire is an inductor. The wings of a fly make a filter capacitor.

micael · 28th July 2006, 01:56 AM

In any case, if i use vero-board is there any chance for the receiver to receive a 433MHz signal?

dknguyen · 28th July 2006, 02:07 AM

Use really REALLY REALLY thick wire? I think wire inductance goes down as the wire gauge gets larger, but I could be wrong.

kchriste · 28th July 2006, 03:48 AM

What you need to do is determine which pins on the SIP have RF on them. Keep the traces short and the parts connected to the RF pins close together. Keep in mind that you want to group the various stages (RF IF & AF) apart from each other at the same time. Bypass the SIPs power supply well (close to SIP) with several caps in parallel; say, 100pf, 1000pf and 0.1uf. These RF SIPs are meant to be mounted on a multilayer board with a layer dedicated as a ground plain so a veriboard is far from ideal, but with some carefull design you should be able to pull it off.

JimB · 28th July 2006, 08:28 AM

One of the reasons behind using an RF module is that all the RF stuff is contained in the module.
I do not know where

"Never place a Transmitter or Receiver directly into Vero-Board or any similar prototyping board. This will severely restrict the range. Rather, use small lengths of wire from the prototyping board to the pins of the Transmitter or Receiver."

comes from, but lets consider the modules connector pins.

From an RF point of view, the only ones to worry about are the Antenna and Ground pins.
I suggest that you connect the Ground pins together using a short wire, and that they are connected to a large amount of metal work or a piece of wire of similar length to the antenna, thus forming a "ground plane" or "counterpoise" for the antenna to work against.
The antenna should be a wire connected as directly as possible to the antenna pin of the module. What I suggest here is that the module antenna pin is soldered into the veroboard and the antenna wire is soldered into an adjacent hole. Then isolate the two antenna connection holes from the rest of the strip on the veroboard by cutting the tracks immediately either side of the antenna connections.

JimB

**Nigel Goodwin** · 28th July 2006, 08:54 AM

Quote:

Originally Posted by micael

I m using FM-RRFQ1-433 FM Receiver , SIL Package, 433MHz module which has to be mounted on a Vero-Board so...how i ll keep it away from the vero board????

Check my PIC RF tutorial, notice that it uses Veroboard! - BUT, I remove all unused strips and parts thereof. Don't really know if you need to do that?, as all the high frequencies are on the module, and not the external connections (apart from the aerial connection) - but it's simple and easy to do, so you may as well?.

micael · 29th July 2006, 03:43 AM

Hi,
Thanks Nigel that was quite helpful,
Is it ok if pin 2 ( data input) of FM-RTFQ1-433 is connected to Vcc just to test if the transmitter is actually transmitting?
And for receiver FM-RRFQ1-433 to always operate in standby mode and wake up only when there is a signal at 433.9MHz, pin 15 should be connected to ground?
(FM-RRFQ1-433,FM-RTFQ1-433->datasheet->
http://www.winpicprog.co.uk/download/wireless.pdf )

**Nigel Goodwin** · 29th July 2006, 08:41 AM

It's transmitting all the time it's powered up, the data input just alters it's frequency - you can't just trigger it with DC, as it's AC coupled, which is why you can't send plain RS232.

I've never looked at pin 15, so can't comment on it? presumably the datasheet explains it?.

micael · 31st July 2006, 08:54 PM

May i ask how is possible to connect a zener diode without having to replacing it (explodes) every time 5V passes through it???
Im trying to connect a 3.3V zener diode in series with 68 Ohm resistor in a circuit supplied by 5V (as shown in www.winpicprog.co.uk , in pic tutorial wireless board) However my diode overheats each time im trying to connect it to 5V.

audioguru · 31st July 2006, 09:52 PM

Quote:

Originally Posted by micael

May i ask how is possible to connect a zener diode without having to replacing it (explodes) every time 5V passes through it???

5V doesn't pass through the zener diode. The 68 ohm resistor in series with the zener diode limits the current in the zener diode to only 25mA. Therefore the zener diode heats with a max of only 3.3V x 25mA= 82.5mW.

You probably have the 3.3V output of the zener diode connected directly to 5V, so the 68 ohm current-limiting resistor is shorted.

micael · 31st July 2006, 10:16 PM

"You probably have the 3.3V output of the zener diode connected directly to 5V, so the 68 ohm current-limiting resistor is shorted."
Well yes that's what i ve done....ehm ok i ve connected both ends of 68 Ohm resistor along the Stripboard's track line.... and the diode was indeed directly connected to 5V.....

audioguru · 31st July 2006, 10:46 PM

The zener diode is not supposed to connect directly to 5V. It is supposed to have the 68 ohm resistor in series with it to limit the current.
Here is the schematic:

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28th July 2006, 12:47 AM	(permalink)
micael	stripboard's capacitance between adjacent tracks and received signal Hi "Never place a Transmitter or Receiver directly into Vero-Board or any similar prototyping board. This will severely restrict the range. Rather, use small lengths of wire from the prototyping board to the pins of the Transmitter or Receiver." The question is were to put the transmitter or receiver modules and their antenna?? Why the stripboard's capacitance between adjacent tracks affects so much(reduced) the received signal from 17.3 wire antenna placed on a striboard?

28th July 2006, 12:57 AM	(permalink)
dknguyen	Your quote implies that the transmitter/receiver should be separated from the proto board by long wires- that's where it is telling you to put the transmitter/receivers and antenna- away from the vero board, it doesn't matter where exactly- I think that the inductance introduced by the wires is supposed to counteract the parasitic capacitances on the veroboard. Radio circuits by their nature work with specific frequencies and parasitic inductances and capacitances (like those caused by all the generic traces on the proto-board cause problems. Imagine an R-C filter. Good right? Now imagine that instead of just plain old perfect ideal wires connecting the R and C, the wires connecting them are REAL wires. Real, really messy wires that loop all over the place and branch off and meet each other again (like all the unused traces on the vero-board). The lines that are wires in your circuit schematic aren't lines anymore, they are other capacitors and inductors. They essentially introduce extra capacitors and inductors and resistors into your circuit which will cause it to work differently. When your circuit is a radio circuit and has to be tuned precisely to work, these extra parasitic components cause problems. In the case of the R-C filter they will change the frequency that your filter will work at. Last edited by dknguyen; 28th July 2006 at 01:00 AM.

28th July 2006, 01:26 AM	(permalink)
micael	I m using FM-RRFQ1-433 FM Receiver , SIL Package, 433MHz module which has to be mounted on a Vero-Board so...how i ll keep it away from the vero board????

28th July 2006, 01:31 AM	(permalink)
audioguru	433MHz is darn high. Nearly microwaves. A couple cm of wire is an inductor. The wings of a fly make a filter capacitor. __________________ Uncle $crooge

28th July 2006, 01:56 AM	(permalink)
micael	In any case, if i use vero-board is there any chance for the receiver to receive a 433MHz signal?

28th July 2006, 02:07 AM	(permalink)
dknguyen	Use really REALLY REALLY thick wire? I think wire inductance goes down as the wire gauge gets larger, but I could be wrong.

28th July 2006, 03:48 AM	(permalink)
kchriste	What you need to do is determine which pins on the SIP have RF on them. Keep the traces short and the parts connected to the RF pins close together. Keep in mind that you want to group the various stages (RF IF & AF) apart from each other at the same time. Bypass the SIPs power supply well (close to SIP) with several caps in parallel; say, 100pf, 1000pf and 0.1uf. These RF SIPs are meant to be mounted on a multilayer board with a layer dedicated as a ground plain so a veriboard is far from ideal, but with some carefull design you should be able to pull it off. Last edited by kchriste; 28th July 2006 at 03:50 AM.

28th July 2006, 08:28 AM	(permalink)
JimB	One of the reasons behind using an RF module is that all the RF stuff is contained in the module. I do not know where "Never place a Transmitter or Receiver directly into Vero-Board or any similar prototyping board. This will severely restrict the range. Rather, use small lengths of wire from the prototyping board to the pins of the Transmitter or Receiver." comes from, but lets consider the modules connector pins. From an RF point of view, the only ones to worry about are the Antenna and Ground pins. I suggest that you connect the Ground pins together using a short wire, and that they are connected to a large amount of metal work or a piece of wire of similar length to the antenna, thus forming a "ground plane" or "counterpoise" for the antenna to work against. The antenna should be a wire connected as directly as possible to the antenna pin of the module. What I suggest here is that the module antenna pin is soldered into the veroboard and the antenna wire is soldered into an adjacent hole. Then isolate the two antenna connection holes from the rest of the strip on the veroboard by cutting the tracks immediately either side of the antenna connections. JimB __________________ Experience is directly proportional to the value of the equipment ruined.

29th July 2006, 03:43 AM	(permalink)
micael	Fm-rtfq1-433 Hi, Thanks Nigel that was quite helpful, Is it ok if pin 2 ( data input) of FM-RTFQ1-433 is connected to Vcc just to test if the transmitter is actually transmitting? And for receiver FM-RRFQ1-433 to always operate in standby mode and wake up only when there is a signal at 433.9MHz, pin 15 should be connected to ground? (FM-RRFQ1-433,FM-RTFQ1-433->datasheet-> http://www.winpicprog.co.uk/download/wireless.pdf ) Last edited by micael; 29th July 2006 at 03:48 AM.

29th July 2006, 08:41 AM	(permalink)
Nigel Goodwin	It's transmitting all the time it's powered up, the data input just alters it's frequency - you can't just trigger it with DC, as it's AC coupled, which is why you can't send plain RS232. I've never looked at pin 15, so can't comment on it? presumably the datasheet explains it?. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

31st July 2006, 08:54 PM	(permalink)
micael	zener diode in RF circuits May i ask how is possible to connect a zener diode without having to replacing it (explodes) every time 5V passes through it??? Im trying to connect a 3.3V zener diode in series with 68 Ohm resistor in a circuit supplied by 5V (as shown in www.winpicprog.co.uk , in pic tutorial wireless board) However my diode overheats each time im trying to connect it to 5V. Last edited by micael; 31st July 2006 at 08:57 PM.

31st July 2006, 10:16 PM	(permalink)
micael	exploding zener diode "You probably have the 3.3V output of the zener diode connected directly to 5V, so the 68 ohm current-limiting resistor is shorted." Well yes that's what i ve done....ehm ok i ve connected both ends of 68 Ohm resistor along the Stripboard's track line.... and the diode was indeed directly connected to 5V.....