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The "perfect" Lynx....


Level42

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Hope to install the variable clock mod tonight,

 

Did some googling about battery replacements of sorts. Ideally I'd love to be able to build a "permanent" battery inside the Lynx which I will "never" have to take out again, so something like an iPad battery basically.

I could actually live with 6 standard Nimh AA cells but they should be able to,recharge inside the Lynx....

I want this mainly because I don't want to remove the batteries and charge them in a separate charger all the time, plus, I only have a 4 slot charger which markes charging 6 batteries even worse....I guess I just got spoiled by modern day battery powered stuff.....

 

....so that would mean adding a charging circuit....I have no clue where to begin their because of the rather complicated power supply section of the Lynx....

 

However IF it would be possible to add a charging circuit, why not go with Lipo batteries to really get that iPad feel....

 

So I googled a bit for flexible (or at lease pretty flat) Lipo batteries and sadly it seems all I can find are large order ones on Alibaba, like the one I posted a picture of.

I think it should be possible to fit two of such batteries inside. Two in series would produce about 7V which should be enough to keep the Lynx happy.

 

Of course Lipo's have their dangers too and require a good protection and charging circuit....

 

Anyway, has anyone actually done this yet ?

post-25272-0-19661100-1470162796_thumb.png

Edited by Level42
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I haven't done it yet, but it really won't be that difficult.

 

I was planning on one just putting a single 3300mah panasonic cell in, and using an Adafruit powerboost 1000C charger/5V booster circuit. From there, you basically perform the 5V mod on the Lynx. Instead of hooking up the RECOM DC/DC regulator, you wire in the output from the 1000C. Break up some traces near the lynx power jack and you can re-use the stock jack as the input and just build a custom USB cable to play/charge off a 2A brick.

 

I don't really want to mess with series Lipo as that becomes a mess with a balancing charger/etc. The cool thing about the 1000c is that you could charge and play at the same time. The issue you're still going to have to solve though is that you'll need an actual power cut switch to turn off the 1000C when the Lynx is off, otherwise it will slowly suck the battery dry. You could place a switch neatly in the old battery compartment area behind the stock cover in front of the new batt. If you did things right, you could even mount a 18650 battery holder so you could replace the battery when it goes bad over the years.

 

When I find a donor Lynx, I'll attempt it.

 

Here's the battery I'm thinking of: https://www.amazon.com/Panasonic-NCR18650B-3400mAh-Rechargeable-Battery-Green/dp/B00DHXY72O/ref=as_li_ss_tl?ie=UTF8&linkCode=ll1&tag=atariage&linkId=73ba9ac22cd6229e44f1e7af0280a94f

And the charging circuit: https://learn.adafruit.com/adafruit-powerboost-1000c-load-share-usb-charge-boost/overview

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Good info, thanks !!!

 

SO, I just wired up the tiny oscillator PCB and tested it with a scope...works nicely.

 

Now I checked schematics and the crystal is "directly" connected (except for a 100 ohm resistor) to Mikey. Mikey seems to have XTALI and XTALO.....guess I need to hook up to XTALI :) I didn't remember that the crystal was directly placed under the cartridge connector....not the best spot for our goal....but I've managed to do the regular 24 Mhz hack before :)

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.....and suddenly I feel some fear......this crystal is hooked up to Mikey almost directly (apart from the 100 Ohms resistor).....ac crystal is of course a passive part in that it just responds to an output voltage.....now this oscillator PCB of course puts out a clock signal at a certain voltage. The installation instructions say it's OK to remove the crystal and hook it up directly but.....I'm a bit unsure now....

 

I'm pretty sure I'm going to have to use the input (XTALI) of course because I assume the output puts a voltage on the crystal to get it to resonate...but there is absolutely nothing between the output of the little PCB and the XTALI, no resistor or anything....and it does pump out about 5 V peak-peak.....

Does anybody know how Mikey handels the crystal ? Is there a schematic of Mikey ?

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OK, I overlooked the 10 Mohm resistor which is in parallel with the crystal....OK I'm going to take a small gamble and hook it up to XTALI.....let's hope I don't get any smoke !

 

Are there any drawings with the PCB lay-out of the Lynx I by the way ?

Edited by Level42
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Wooohooooooo SUCCESS !!!! IT WORKS :)

 

(And it doesn't even seem to matter to what point I connect the output of the oscillator PCB :D)

 

Uploading video as we speak.....

 

One thing: tested it with SainT's SD card and it doesn't seem to like higher frequencies than standard....it goes from INSERT GAME to displaying the menu version and "Reading menu"but hangs there. HOWEVER, if set to (about) 16 Mhz it works fine, you can load a game and once the game is running you simply increase the speed to your liking .....this works just fine :)

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Yup....I much prefer the I. I have a II too though :)

 

OK guys, here's the video demonstrating (the world's first ?) Lynx with variable adjustable game speed :)

 

 

This might be fun for other projects too (Atari 8 bit.....FINALLY running games at NTSC speed on a PAL system.....en beyond ;)) or maybe even Arcade machines :)

Edited by Level42
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great to hear, I love hacking stuff ;)

 

cow dog, that Adafruit site actually provides some very good information about Lipo/li-ion batteries:

https://learn.adafruit.com/li-ion-and-lipoly-batteries

 

I really liked reading that because it's good, honest, clear info.

 

(There is also great info about all other sorts of batteries: https://learn.adafruit.com/all-about-batteries/overview )

 

Definitely going to order that 1000c board but it's out of stock at the moment. I'd also order their battery, must be OK quality if they sell it, I know they must be China made but I'm not very sure to order a random battery from China.....as the explanation indicates, some of those batteries lack the protection PCB,s and I simply want my Lynx to be safe.....(I've heard people had replaced their iPhone batterie only to catch fire)

I'm a bit sad that their highest li-ion is 2500mAh though....I think there is space for a larger battery inside the Lynx I....

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What if this would fit......

 

http://nl.aliexpress.com/item/10AH-large-capacity-lithium-battery-3-7v-lithium-polymer-battery-10000mAh-high-current-power-battery-lithium/32645534218.html?spm=2114.13010308.0.37.A17gdS

 

10000maH / 350ma = 28,57 hours of play :grin: :grin: :grin:

 

 

But this one lacks a protection circuit.....

 

The battery's adafruit offers are of the PKCELL brand. I reached their website and the largest capacity they offer is 5100mAH but I can't find it for sale on eBay/Aliexpress or anywhere else in fact...

 

But first I'd need to figure out how much space there really is inside the Lynx 1. I'd prefer not to remove the battery tray part, but this could be modified to make more room maybe. I also noticed that the back of the Lynx has little pins apparently to support the battery tray. These could be cut off to make some more room. The battery lis could be glued in permanently which also makes it possible to get rid of the ridge for that lid...

By the way, I actually found a source here in The Netherlands that still has a large stock of Adafruit Powerboost 1000C's and it's close enough for me so I can drive up there to get one. Their a bit more expensive but no shipping costs makes it worthwhile again...

Edited by Level42
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This one might be a more realistic option:

http://nl.aliexpress.com/item/Good-Qulity-3-7V-6000mAH-Real-5200mAh-Li-ion-battery-for-CHUWI-V88-ONDA-V971-Pipo/32214071816.html?spm=2114.13010308.0.42.A17gdS

 

Sizes:

3.2*82*150mm a bit long and wide for the Lynx case but very thin with 3.2 mm....

 

​Trouble is without actually having the battery it's hard to know if it will fit....

 

6000mAH would still gain a theoretical 17,14 hours of play :D

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LOL :)

 

Well I just puzzled a bit with the Lynx 1 case. I thought it would be ideal to get completely rid of the battery tray inside the case. It would save a bit of weight, make "a lot" of space and....well it's not needed anymore once the lipo is in there...

 

However the first and most important problem is that the cartridge cover will not be supported anymore. And even though I have the SD card, we still need to open it to update the SD card every now and then...

So that part of the battery tray has to stay.

On the other side, when I completely remove the tray, the large screws seem to "lift up" the back cover of the Lynx when I try to screw them down.

So maybe I will have to keep this two far ends of the tray in, but cut out the largest area of the middle part.

 

Next I measured how much space there is.....since I still have the original screen, there is only about 7 or 8 mm. between the back-cover and the top of the old LCD lighting tube. However, this is by far enough to install a battery that's only 3.5 mm high.....

 

Now, if I'd install the McWill LCD it would create something like a "plane hangar" of space between the Lynx PCB and the back cover, it would be about 2 cm. There would even be more space because the old voltage PCB for the screen will be removed.

However, I don't think that McWill's LCD is going to be happy with any speed modding....so I'm now a bit in doubt....will I keep the original screen on this Lynx, install all the other mods I've thought about and put a McWill in the Lynx 2 I have ? Or should I just forget about the speed-mod.....mmmm tough decision....

 

O well, I will order the new LCD anyway and I can always remove the speed hack, it's not there in permanently installed anyway...

 

I wish I could find a PCB lay-out drawing of the Lynx 1 .....would make finding stuff a lot easier.

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@Cowdog: did you have idea as to where to hook in the output of the Adafruit Powerboost 1000C ?

 

It would be nice to get rid of the problematic FET and Zener diode for sure. The Powerboost 1000C should already provide a nice and clean 5V with which the Lynx should be happy so keeping them in there would only mean extra loss of energy and risk of them going bad (although in that case, you'd simply still have only 5V on the chips).

 

However, the problem is that the on-off push buttons are also tied into this circuit....and of course it would be nice to keep the on-off switching like the original.

 

However, the Adafruit Powerboost 1000C has an enable input that can be used instead....with a small slider switch. But this is on/off, not a "trigger" circuit like the push buttons on the Lynx.

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@Cowdog: did you have idea as to where to hook in the output of the Adafruit Powerboost 1000C ?

 

It would be nice to get rid of the problematic FET and Zener diode for sure. The Powerboost 1000C should already provide a nice and clean 5V with which the Lynx should be happy so keeping them in there would only mean extra loss of energy and risk of them going bad (although in that case, you'd simply still have only 5V on the chips).

 

However, the problem is that the on-off push buttons are also tied into this circuit....and of course it would be nice to keep the on-off switching like the original.

 

However, the Adafruit Powerboost 1000C has an enable input that can be used instead....with a small slider switch. But this is on/off, not a "trigger" circuit like the push buttons on the Lynx.

Well, the big problem is what the draw at idle on the powerboost will be. Most likely it will be around 5ma, so just sitting there with the lynx "off" it would be sucking out 5ma, so after a week of just idling it would probably drain the battery pretty significantly.

 

Ideally it would be nice to use the soft power switch somehow without the draw.

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As far as I understand it the board draws only 20uA (0.00002 A) when turned off.

 

That would mean it would take 250,000 hours (or 10417 days, or about 28,5years !!!!) to fully drain a 5000mAh battery.........when turned off :D

 

Quote from Adafruit's website:

 

and low quiescent current: 5mA when enabled and power LED is on, 20uA when disabled (power and low batt LED are off)

 

https://learn.adafruit.com/adafruit-powerboost-1000c-load-share-usb-charge-boost/overview

 

 

I'm a bit more worried about the heat it will generate inside the Lynx case. It can be converting up to 1,8A when it's charging the battery AND powering something at the same time...not sure if that would happen in the Lynx but even so....that is a lot of energy which will generate a fair amount of heat....

 

https://learn.adafruit.com/adafruit-powerboost-1000c-load-share-usb-charge-boost/faq

 

Maybe one of the best things of using this board is that whatever happens on the board, even in the very worst case it will only pass-on the battery voltage, which is ALWAYS lower than 5V (typically between 4,2 and 2.8 volts.... :D

Edited by Level42
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Exactly, its a pretty safe bet. The problem is that it only goes into quiescent mode when you shunt the enable pin to ground. In other words, you're going to need to have a power switch to do that. Otherwise, it's just going to be on idling at 5ma. You could probably remove the LED and reduce drain another 1-2ma. I'm just not sure of a way you could have the stock lynx power button enable the unit and disable the unit, since the circuit that does the lynx power buttons needs 5V to watch for those button presses, which means you'd need the regulator on.

 

If atari had just used a freaking physical power switch like every other console... soft power is cool, but such a pain to mod around.

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Yep exactly my thoughts..... I've been breaking my head if it would be possible to keep using the original on-off buttons....it should be possible but would be a lot of hacking though, too much IMHO.

 

I think I'll go for a switch. The main reason for this is that it will make it possible to get rid of the entire original power section. The AC detection line has to be tied high, there is no need for the Lynx to shut itself down anymore so I won't bother with that.

 

I'm still in doubt though.....will I go for the McWill LCD first ? I think so, as this will give SO much room in the Lynx 1 :D

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Or, I just figured out an alternative! Gut the Lynx's power and start button circuitry.

 

Tie both the On and Off button in parallel to a LTC2950 pushbutton controller chip, which is tied to the enable pin on the powerboost. The pushbutton controller IC uses 20uA of power and when you push the On button, it would send the enable to the regulator, firing it up. Then if you hold the On or Off button down for a second, it powers the whole thing off. Now you've saved your buttons, and power too.

 

http://www.linear.com/product/LTC2950

 

I may have to try this!

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