Ramsey remote repeater kit mod

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
Post Reply
m2mike
Posts: 13
Joined: Wed Dec 07, 2005 1:01 am
Contact:

Ramsey remote repeater kit mod

Post by m2mike » Fri Dec 09, 2005 8:46 am

Hello,

I have ordered the RRW1AC Wireless IR/RF Remote Transmitter and the RRW1BC Wireless RF/IR Remote Receiver from Ramsey Electronics. I have a question. How would I mod it for a different frequency? On the transmitter, is it as simple as changing the SAW resonator at X1? Will I also need to change a capacitor at C7 or C8?

I don't have an LCR meter for measuring components. I probably need one. I know that I can calculate this accurately with the math located here: http://en.wikipedia.org/wiki/Colpitts_oscillator

So what about the receiver? How would that be adjusted to receive at a different frequency? Is it as simple as changing the 3.3149 Mhz crystal at X20?

Can someone provide me with the correct calculations?

The manuals for these can be viewed here:

http://www.ramseyelectronics.com/downlo ... /RRW1A.pdf
http://www.ramseyelectronics.com/downlo ... /RRW1B.pdf

User avatar
Edd
Posts: 885
Joined: Sun Jan 27, 2002 1:01 am
Location: Dallas Tx
Contact:

Re: Ramsey remote repeater kit mod

Post by Edd » Sun Dec 11, 2005 12:39 am

What?.....no takers?
Can you fill us in on the specific application in which you are going to utilize the devices? (Hopefully, that basically would answer the question as to why you would want operation on other than the designed frequency of the units ?)
Those units are offering quite a degree of performance within their integral designs.
As for the RF transmitter section of the sending unit, in the olden times that would have required the use of an initial crystal osc ckt and then using freq multiplier stages to reach up to the 433 Mhz spectrum. In later years , use of Phase Locked Loop technology would permit the use of an initial LC osc circuit and then its sampling and comparing that divided down freq sample against a stable ref freq in order that correction could be continuously made to that LC osc circuit to lock it on freq. Later yet, a further refinement of that technique would result in actual selective frequency synthesization of a precise desired frequency.
All of the aforementioned techniques being much more than you would want to get involved with…..complexity, expense and developmentally for a project like this.
HOWEVER, this circuits specified Surface Acoustic Wave resonator is just introduced within the feedback loop of an osc circuit and has optimal coupling within its designed pass band therefore, that is the freq at which it is going to permit oscillation to occur.
Result, a very simple / stable oscillator with the SAW being responsible for the tight freq stability.
Their selection of that particular SAW freq is probably due to the lower cost ….due to mass demand…of European market receivers using it as their LO osc freq in superhet design receivers outputting a 500 Kc IF freq from an initially received 433.92 Mhz signal. They are used in Car alarms with their key fobs, Home keyless entry, Security systems, Remote fan/light control, Garage door openers, etc.. With us also doing the same thing Stateside, except at a different allocated frequency(s).

Using other less commonly used SAW freqs will demand a price premium, as well as the purchase quantity factor.

Here are three progressive degrees of manuf data resources on the RRW1B’s MICREL MICRF001BN receiver section chip:

http://www.micrel.com/product-info/prod ... f001.shtml
http://www.micrel.com/_PDF/micrf001.pdf
http://www.micrel.com/_PDF/App-Notes/an-22.pdf


“LC based transmitters simply will not do!”….quoted as per page 2 within App note 22
as in referencing normal superhet designed receivers, however they slightly attest as to their receiver circuitry design being a bit more compliant in the respect of signal capture/lock on range. Particularly ,the transmitter frequency can be allowed to vary by as muchas ±0.4%, or about ±1.5MHz with the receiver using its sweep mode receiving capability. Also, this undoubtedly is not impaired due to the utilization of an internal 2.25 Mhz IF freq BUT with its broad 1 Mhz bandwidth!

Should you HAVE to operate at a different frequency, I submit the lower block of transmitter SAW freqs as possibilities , then you could figure on using the second figure local osc quartz xtal freq as the value that would let the receiver section lock to it and pass it within its IF pass band. The crystal freq is ~130th of the receive frequency. Consult the Ap Note 22 for the precise computational formula.

315.00 Mhz……………2.410700…..Mhz…Local osc Xtal freq
418.00 Mhz……………3.199000
433.92 Mhz……………3.320800


Back to the one SAW xmitter related query:
“Will I also need to change a capacitor at C7 or C8?”……..
since they are a ratio selected pair in the feed back loop scheme of the oscillator, I would expect not, unless you have to select an operating xmit freq way down towards the 300 Mhz bottom freq end of the 300-440 Mhz span capability of the companion receiver.

73's de Edd
[email protected] .........(Interstellar~~~~Warp~~~Speed)
[email protected].........(Firewalled*Spam*Cookies*Crumbs)
;) ;)

I had to take my car in and was worried that the mechanic might try to rip me off. Wheeeeew, was I ever relieved when he told me all I needed was turn signal fluid.
:roll:

m2mike
Posts: 13
Joined: Wed Dec 07, 2005 1:01 am
Contact:

Re: Ramsey remote repeater kit mod

Post by m2mike » Thu Dec 29, 2005 3:23 pm

Thank you Mr. Whatley. I do have one follow up question though. It seems that the included IR sensor module that comes with this kit is limiting what IR signals I can relay. For example, it doesn't relay 56 Khz signals as far as I can tell. I suspect that this is the fault of the IR sensor module. This is labeled as U1 on the RRW1A board. I know that this circuit was designed for 38 Khz remotes so passing a modulated IR signal that is too high or too low might be impossible.

Am I just out of luck? Could I rig something in place of the module that would pass any modulated signal I needed to?

User avatar
Edd
Posts: 885
Joined: Sun Jan 27, 2002 1:01 am
Location: Dallas Tx
Contact:

Re: Ramsey remote repeater kit mod

Post by Edd » Thu Dec 29, 2005 9:35 pm

Well….how ’boot that ?….indeed an unique situation. Seems like EVERYTHING that I have uses the common 38/40 khz spectrum. I would suspect that you would have to get right upon that supplied IR receiver module and swamp it with a 56 khz signal in order to get a response of a couple of inches Soooooo…I would like to know what piece(s) do you have that is using the 56k signal freq ? Thinking about it, I might have one piece….a high line Bang & Olufsen Beomaster…but I think its technique is merely utilizing different continuous frequencies for different functions…..not being pulse code modulated.

First thing to try is to swap units and see if an advertised wide bandwith / filtered IR receiver module will fill the bill for both freqs. The Mouse house has them here:
http://www.mouser.com/index.cfm?handler ... mber=78202

As their:
http://www.vishay.com/docs/82252/82252.pdf


If that fails, the then next logical solution might be to receive the 56 signal on a dedicated mini IR receiver module and convert down to 38 and have that IR emitter shooting towards the 38 unit supplied, that you already have incorporated.

This circuitry should perform the necessities…. …inputting the 56 / interfacing / and driving an IR emitting diode that has its optimal output in the 38 spectrum:
:D

m2mike
Posts: 13
Joined: Wed Dec 07, 2005 1:01 am
Contact:

Re: Ramsey remote repeater kit mod

Post by m2mike » Sun Jan 01, 2006 4:05 am

Aren't all of these modules using a bandpass filter to only pass a particular modulated signal? What if I don't want to limit what signal I pass through it? Forgive my ignorance, but why include a band-pass filter at all with these modules? Is this technically necessary?

User avatar
Edd
Posts: 885
Joined: Sun Jan 27, 2002 1:01 am
Location: Dallas Tx
Contact:

Re: Ramsey remote repeater kit mod

Post by Edd » Tue Jan 03, 2006 12:33 am

The band pass procedure is used to provide enhanced noise immunity of the units, along with an accompanying range performance. Review the data supplied on page 6 of the data sheet. Circuit wise, a reference signal direct from the detector is compared with a like signal that has been additionally band passed and a cumulatively developed corrective compensation is passed on to the systems control and automatic gain circuitry.
There is a great bit of refined circuitry enclosed within those small packages and they do one great job.


73's de Edd
[email protected] .........(Interstellar~~~~Warp~~~Speed)
[email protected].........(Firewalled*Spam*Cookies*Crumbs)
;) ;)

Why do gas stations lock their bathrooms?
Are they afraid that someone will go inside and clean them ?

:roll:

m2mike
Posts: 13
Joined: Wed Dec 07, 2005 1:01 am
Contact:

Re: Ramsey remote repeater kit mod

Post by m2mike » Tue Jan 03, 2006 4:08 am

Yes, I have no doubt the packages do their intended job, but none of them receive on the frequency in KHz that I need. I really just want to be able to band pass the IR at any modulation. It would be nice to go as low as 1 Khz and 2 Khz and as high as 56 Khz. Is this impossible? I don't know of any modules that go that low. Am I out of luck with this board?

Would it be possible to improvise something with the same board, but different components? I'm out of ideas.

m2mike
Posts: 13
Joined: Wed Dec 07, 2005 1:01 am
Contact:

Re: Ramsey remote repeater kit mod

Post by m2mike » Wed Mar 15, 2006 8:33 am

315.00 Mhz……………2.410700…..Mhz…Local osc Xtal freq
418.00 Mhz……………3.199000
433.92 Mhz……………3.320800

Can someone recommend a supplier for the above crystals and other crystals as well? I have already perused Jameco and Digikey and didn't find anything.

User avatar
Edd
Posts: 885
Joined: Sun Jan 27, 2002 1:01 am
Location: Dallas Tx
Contact:

Re: Ramsey remote repeater kit mod

Post by Edd » Thu Mar 16, 2006 12:54 am

.


I can see your having remote infrared equipment operating at the extremely common frequencies of 38 Khz and the somewhat rarer 56 khz freqs , but WHAT in the world do you have that would be operating at 1 and 2 Khz infrared frequencies ?
Maybe we just need to be filled in on exactly what is contemplated on being done with this equipment.

I interpreted /assumed the application to be that of an infrared remote sending a signal within a room and it being picked up by a companion mated IR detector block that then strips off the serial pulse data stream modulation from the IR signal and then serially pulse modulates an RF transmitter module to reach a wall isolated / room / distantly located companion RF receiver module which then serial pulse modulates an infrared LED at the other location. That LED beam then activates a companion piece of equipment of that specific remoted hand unit. The other alternative was for a second IR receiver in the 56 Khz pass band to also be located at both sites. Now we?re wanting to go down into the audio spectrum ? also ?...please clarify.

Solely to the specified Xtal frequency question, JAN Crystals, Crystek Crystals or International Crystals will make a quartz crystal of any frequency that you need.
http://www.jancrystals.com
http://www.crystek.com/crystals/quartzc ... iption.htm
http://www.icmfg.com

BUT, that would be of no assistance in the IR bandpass problem , as that would only be shifting RF handshaking frequencies between RF Xmitter and receiver modules.

One final approach in mind , but would need a full fill in on prezactly what is trying to be accomplished.

Lastly, have you tried the whole system with the 38khz IR receiver block and does it give you the required range and room coverage ?


73's de Edd
[email protected] .........(Interstellar~~~~Warp~~~Speed)
[email protected].........(Firewalled*Spam*Cookies*Crumbs)
;) ;)

If at first you DO succeed, at least, try not to look so astonished!
:eek:


.

dyarker
Posts: 1721
Joined: Fri Aug 22, 2003 1:01 am
Location: Izmir, Turkiye; from Rochester, NY
Contact:

Re: Ramsey remote repeater kit mod

Post by dyarker » Thu Mar 16, 2006 1:25 am

?????? confusing 1 - 2Kbps data rate with 38KHz or 56KHz modulation of IR ????????
Dale Y

m2mike
Posts: 13
Joined: Wed Dec 07, 2005 1:01 am
Contact:

Re: Ramsey remote repeater kit mod

Post by m2mike » Thu Mar 16, 2006 6:06 am

I no longer require a 1 to 2 Khz bandpass, but thanks for the links for the crystal. I just need the transmit and recieve frequency, which is almost done now. Thank you.

m2mike
Posts: 13
Joined: Wed Dec 07, 2005 1:01 am
Contact:

Post by m2mike » Thu Jun 08, 2006 3:15 pm

I have successfully modded a RRW1A transmitter to use a different frequency. This was as simple as using a different SAW resonator in place of the one provided, but I seem to be having trouble with the RRW1B receiver. I changed the crystal oscillator at X20 to a different frequency so as to change the receiving frequency, but it still won't work. If anyone else tries this mod, I would be interested in hearing about your successes or failures.

Maybe I have a bad component? I have adjusted R20 to get the "proper squelch", but that doesn't seem to make a difference. I have an abundance of these new oscillators so I might get a new receiver if necessary. Any suggestions on what I should test to get this working?

User avatar
Edd
Posts: 885
Joined: Sun Jan 27, 2002 1:01 am
Location: Dallas Tx
Contact:

Post by Edd » Sun Jun 11, 2006 6:03 am

.

It seems like you neglected to give the frequency of the different SAW resonator subbed into the transmitter.
Likewise, as well as what frequency value of local oscillator crystal that you then subbed into the receiver in
order to coincidentally shift its receive frequency to within the capture range of the new xmit freq.
.
73's de Edd
[email protected] ...........(Interstellar~~~~Warp~~~Speed)
[email protected].........(Firewalled*Spam*Cookies*Crumbs)

…….Image….. If It Wasn't For The Last Minute, Nothing Would Ever Get Done

.

m2mike
Posts: 13
Joined: Wed Dec 07, 2005 1:01 am
Contact:

Post by m2mike » Tue Jun 20, 2006 7:27 pm

Okay, suppose it was modded to 418 Mhz. That means the recieving crystal at X20 on the RRW1B would have to be 3.1990 MHz. Suppose I wanted to get the part from www.vectron.com. What would be the appropriate part number?

Also, it seems like the resistance goes up when the frequency changes. Perhaps a change from 200 Ohms to 400 Ohms? I don't actually know since I don't have a multimeter.

Post Reply

Who is online

Users browsing this forum: No registered users and 9 guests