JP1 Remotes

SilentBob · Joined: 12 Feb 2005 Posts: 29

Sorry, I've been away for a couple of days, yes I was definitely talking about RF strength.

I never have problems with direct IR, but I get tired of doing windmills with my arm trying to find the "sweet spot" for the RF when I am in distant rooms.

The reason I was asking about boosting the voltage is that my RF really seems to suffer as the batteries get old. New batteries obviously produce much better performance, I just didn't know if I could exagerate that by over volting it.

I am definitely not as well versed in signal electronics as some of the experts in here, so I will ask this question as well.

Could a frequency counter such as
this:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5757379838
http://www.optoelectronics.com/cub.htm
or this:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5756787056
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5757993102

Be used to successfully tune the remote, or is there something else that I'm missing?

Thanks.

SilentBob · Joined: 12 Feb 2005 Posts: 29

Just thought I would post an update for anyone who is following/cares.

One nice thing about acquiring several items for a ridiculously low price is that it encourages experimentation.

Against the advice of those in the forum, while I had the back of one of my 9910s popped off, I wired in a 9V battery connector to the +/- power terminals, and hooked it up to a 9V battery.

Wow!!! not only does it seem to work, I now have incredible transmit power, it is like being in the same room as the receiver from anywhere in my house. I don't know if the over voltage will shorten the life of some of the components.

One thing I did notice, is that when the backlight is turned on, resistor R54 gets rather hot. I don't know if there is a way to resolve that problem or not. But other than that, it seems to work perfectly.

I'm going to look at modding the plastic case to hold the 9V battery and see how long this thing lasts until something dies.

The Robman · Posted: Tue Mar 15, 2005 12:28 pm Post subject:

Hey Bob,
Please keep us posted on how this mod works out. I'm concerned that there might be side effects of running 9v through circuitry designed for just 6v, so I'd like to know what happens to your remote.
_________________
Rob
www.hifi-remote.com
Please don't PM me with remote questions, post them in the forums so all the experts can help!

mr_d_p_gumby · Posted: Tue Mar 15, 2005 3:33 pm Post subject:

Well, for one thing, the S3S8 data sheet lists the absolute maximum power supply voltage as 6.5 volts, so there's a fair chance that the CPU will not like 9 volts for very long. It might work if you could devise a way to apply the higher voltage only to the RF transmitter.
_________________
Mike England

JP1 Group at Yahoo!, JP1 Files Area

SilentBob · Joined: 12 Feb 2005 Posts: 29

I've been using it for a couple of days without a glitch.

After cutting out some of the plastic, I was able to get the 9V battery in the back of the unit, and get the battery cover on, but it still sticks out a bit far so the cover bulges up a bit and pops off easily.

Right now I've just put some duct tape over the battery cover to hold it together....a little ghetto, I realize. I was thinking that some black gaffer's tape might work a little better.

I had also thought about using five of the N-size photo batteries for a total voltage of 7.5V, but for this experiment I'll leave the 9V in. I'm putting relatively heavy usage on this remote because I'm using it as my primary remote since it works so well all over the house.

I would still be curious if anyone has any thoughts about using a frequency counter to try and tune the remote to the desired frequency.

Thanks.

SilentBob · Joined: 12 Feb 2005 Posts: 29

Update:

The remote is still working, but I have run into a slight problem....9V batteries do not have very much capacity.

I noticed today that the performance was decreasing and the remote was saying "Low battery" Which means that it is now worse than having 4 average charged AAA batteries.

I removed the tape and tested the battery voltage...I now have only 5.6V ;(

It will be expensive to replace 9V batteries this quickly. I first started looking at 9V NiMH batteries. I was surprised to see that they only have about 150-250 mAh capacity vs AA NiMH that are now up to about 2500 mAh. Additionally they only operate at 8.4V (which would actually be decent for this purpose) One advantage is their relatively sharp discharge curve, so it should maintain 8.4V up until the end.

However, before I do that, I'm still looking at various Li-ion battery packs for camcorders @ 7.4V If I can find one that is a good size, I may even be able to fit it in without the battery holder bulging out.

I would get better capacity and a shorter self-discharge rate, while still getting above the standard 6V so I would still have the increased range that I am looking for.

I'll keep everyone updated.

SilentBob · Joined: 12 Feb 2005 Posts: 29

Another update for anyone who cares.

The best Li-ion battery pack that I could find was for a Sharp BT-L225
pictures and specifications can be seen here:
http://www.interbatteries.com/product_info.php/products_id/2286

I carefully opened the battery pack and removed the internal cells as well as the protection circuit. (Please note, Li-ion batteries can be quite dangerous...disassembling the case is NOT recommended).

There are two cells that are approximately the diameter of AA cells but they are longer. Even after removing as much plastic as possible, the battery door still bulges out a bit with these cells installed, but it does stay closed now without tape.

I hard-wired the positive and negative terminals of the protection circuit to the + - inputs on the circuit board. Once again, it is important to mention, that it is HIGHLY advisable NOT to bypass the battery pack protection circuit...it is there for a reason.

I have been using this setup for about 2 weeks now. I still get much better transmit power than using the standard 6 volts. I assume that I was getting even better range with the 9V battery when it was fully charged, however, the range provided by the 7.4 volts is enough to make the remote fully responsive in all of my rooms. I occasionally accidentally pick up my regular unmodified remote, and I am quickly frustrated trying to use it from distant rooms.

Last night, though, I thought I finally killed the remote. I tried to use it and there was no response at all. I checked the voltage coming out of the cells and it was down to 6.5V, however, checking the voltage out of the protection circuit, it was 0. The protection circuit in place to both prevent over-charging and over-discharging.

I plugged the cell into the charger and charged it overnight, this morning it was working great again. With this solution I will never get a "low battery" warning, and it looks like it should be recharged every week or two. As is typical with Li-ion cells, I expect that the capacity should increase a bit after a few charging cycles.

I still need to modify the remote to include a charging port so that I do not have to remove the batter pack to recharge it.

Other than that, it seems to be surviving even though it is running in excess of its specified voltage.

I would really like to find a battery pack that uses the smaller square cells that are found in many cell-phone batteries. However, most of those battery packs are built for 3.7V I don't have the knowlege to design a protection circuit for those cells. If anyone has any ideas or suggestions on where to look, please let me know. If I could find smaller cells, I could get the battery door to close completely, which would be nice.

dschaeffer · Joined: 22 May 2005 Posts: 5

I found this post and decided to try it out. I had an HT Pro with disappointing transmit power. Without brand new batteries it struggled even if I was in the same room as the receiver.

I popped the remote open and tried adjusting the capacitor as described in this thread. After adjusting it about 5 times, got it working pretty well. I can now use it 3 rooms away with half dead batteries with no trouble.

I haven't experimented with it any more since it works well enough for me, but it seemed pretty easy to me to get it adjusted correctly.

Tommy Tyler · Posted: Sat Nov 05, 2005 9:40 am Post subject: 9910 Transmit Frequency

Congratulations! It's been almost 8 months since I posted info on trimming the frequency, and you're the first and only one to have had the courage to try it. Glad it improved things, and hope it continues to work well. Thanks for the feedback.

Tommy

dre · Joined: 03 Jan 2005 Posts: 22

Hey Tommy, I actually used your post to 'tune' my 9910 over the summer to great success -- I'm able to control an indoor amp from my backyard now, about 40-50' away, through a double-brick wall.

I'm sure others have had success as well... but we lurkers don't like to say much. Wink

Thanks for all the useful info, and keep up the good work!
/ac

The Robman · Posted: Sat Nov 05, 2005 11:31 am Post subject:

Automator · Joined: 30 Nov 2004 Posts: 1 Location: Chicago, IL

Thanks for the info all.
My 9910 had been dropped so many times that the RF puck broke away from the hot glue mount, broke the coil wires, and the PCB traces at the standoff also. I had to peel 1 turn of wire off the coil to fix it.
To keep this from happening again I have sandwiched a piece of stiff foam rubber between the RF puck and the case.
After I got it all soldered/glued back together I found the range was only about 5 feet. A quick tweak of the trimmer has me back up to about 25 feet.
I found that you can see a red led inside the RF receiver module when things are working properly. There is no need for an external led or speaker.
The trimmer adjustment is easy to do in a dimly lit room while watching for the red LED light inside the RF receiver module. (It is very dim because it is shooting through the IR/purple plastic lens.)

dschaeffer · Joined: 22 May 2005 Posts: 5

Resurrecting an old dead thread for an out of production remote, but I thought I would still post in case anybody cared.

My old HTPRO(URC-9910) died after getting dropped on tile a million times, so I got a new one off ebay. The new one was not working with my old blaster, so I figured they were out of adjustment with each other.

I didn't want to open the remote since I scratched and dented it a lot when I opened the last one. I opened the Blaster unit instead. It also had a variable capacitor. The adjustment screw was covered with some glue that was easily scraped off. I was able to adjust it to get it working well.