Where can I get an AC adaptor?

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machman
machman's picture
Where can I get an AC adaptor?

Hi there can anyone suggest a source for the AC adaptor or a compatible one in the UK? 

I have used one I  already own and it produce the shut down problems a previous thread had outlined. Google has not thrown up a supplier to help. 

I may have to take my chances with Maplins.

Thanx  

 

 

 

 

 

BigKid
BigKid's picture

Hi

I'm also interested in where I can get an adapter? I really would like an RS Media but the only retailer of them in NZ can't supply the correct adapter or a decent charger - they all only take 4 batteries at a time and take all night to charge. The power limitations are the only thing holding me back now. The price has dropped from $600 to $400 here in NZ in a matter of months - think I know why now! I think WowWee would sell a heap more if they sorted out a better power solution. Even when you visit the store the demo models are always flat - I'm yet to get a decent demo. Very frustrating but I still want one!

Interested to know what others think about this and if they found adapters with the correct power requirements.

Nocturnal
Nocturnal's picture

BigKid, Dick Smiths is your friend. Sorry machman, I don't know
any good stores in the UK, but any decent electronics supplier should be
able to set you up with something suitable.

BigKid
BigKid's picture

hehe.. Dick Smith is the sole retailer I was referring too, they can't supply the power adapter and they only have one type of charger that will do D batteries, its one of there 'own brand' ones that takes forever to charge and can only do 4 batteries at time. Did you manage to get a suitable power supply from your branch?

Nocturnal
Nocturnal's picture

I have a bench power supply that I built from scratch a while back to do the job.

 They
are mistaken. What you want is part number M9941 (you can check it on
the website), and then probably something like m9603 to make the actual
connection.

BigKid
BigKid's picture

Thanks Nocturnal, expensive but should do the trick! - so are you a Kiwi?

Nocturnal
Nocturnal's picture

*Laughs* No, I'm an Aussie.

xmb
xmb's picture

Maplin do a 5A switch mode PSU that can be set for 7.5V output and comes with a slection of ends.

http://www.maplin.co.uk/Module.aspx?T...

At £33 it is a bit expensive but may save you money in the long run!

machman
machman's picture

Thanx xmb I will visit my local store with the handbook.It would be helpful if the correct psu were easily available cant find a supplier anywhere.  

Gaza
Gaza's picture

Here's my solution to Media's battery/AC adaptor problem:

Type: After researching various battery types I decide to use Nickel Cadmium rechargeables as replacements for the D Cells. I have not yet bothered replacing the 4 x AA cells with rechargeables as the drain on these is not as high as the D cells and ordinary Alkaline are fine. Nicads are better in high drain situations (Wikipedia has a good description) and Dick Smith sell 4.5Ah D cells, two per pack, for NZ $20. NiMH are the alternative but the best DS have are 2.1Ah and cost the same (the shop assistant tried to convince me to buy NiMH quoting the the tired old nonsense about memory effect but I'd done my research and knew what I wanted). To recharge a nicad you generally put around 1.5 times the Ah capacity back into them. The DS batteries have a recommended standard change of 16hrs @ 450mA or 1.6 time their Ah rating.

Voltage: Standard D cells are 1.5V per cell or 9V total but nicads (and NiMH) are 1.2V per cell or 7.2V total so are nicad suitable? The short answer is yes. The voltage from standard cells reduces as they discharge whereas nicads stay pretty close to 1.2V until discharged and then they collapse. So when they designed Media for standard batteries the designers had to cater for less than 9V anyway. And note that the recommended adaptor is 7.5V.

Weight: The weight in the feet is apparently an important factor in getting Robosapiens walking correctly. Six Alkaline D cells weigh in at 800 grams whereas the nicads weigh 650g. I have had no problems with my Media walking with nicads but if required a few lead sinkers would make up the difference.

Recharging; I wanted to to recharge the batteries without taking them out of the feet. Could the conveniently supplied power socket in Media's right foot be used? I traced out the circuit on the power supply board that is in the foot (is there anyway to upload the circuit diagram here?) and there are two points to note: first when a plug is inserted into the DC supply socket, it disconnects the D cell battery negative lead and second that the D cell positive lead is fed via a set of protection diodes. For the technically inclined these are 1N5817 Schottky diodes so they only drop around 0.4V but the designers have had to put three in parallel to handle the current as these diodes have a limit of 1A. These diodes are there to prevent current flowing back into non-rechargeable batteries. Now this is exactly what we want with recharagebles so I soldered a shorting link across the diodes, gaining 0.4V of valuable battery voltage along the way.

The next problem was the battery disconnect switch in the power plug. If you have 9V from the D cells and you plug in the recommended 7.5V external power pack, the batteries will still be supplying motor current so the switch is necessary to disconnect the batteries. The Manual says that "RS Media will not perform and leg actions or bend at the waist while running from an adaptor" but I suspect that this is simply because the adaptor cannot supply the required current. Also I'm sure that the small switch in the DC socket is not designed to handle the high amperage that Media's motors draw and will eventually be a failure point. So another shorting link across the switch and we are almost ready to go.

Charger: The recommended 450mA standard charge is pretty high and I didn't what to have to buy another plug pack. I have several 12V, 300mA ones lying around and working backwards gives (4.5Ah x 1.6A) / 0.3A = 24h, i.e. at 300mA it will take 24 hours to fully recharge. All I needed was couple of high wattage resistors (15ohms in total) to drop the excess voltage and provide a semi-constant current supply and we are away. I can now fully operate Media while recharging so 24 hours is not a problem .

The one last problem is overcharging; this is death to nicads and its how I killed my previous battery drill (plugged it in one weekend and forgot about it until the next weekend!). At the moment I don't have a solution to this other than to set an alarm on my phone/watch/whatever but some form of timer is going to be necessary. Must check out the local electronics shops and see if they have a simple 24 hr, one shot, mains timer that I can plug the power pack into. I could use it for my new drill as well.

Hope this helps anyone else who is looking for a rechargeable solution.

xmb
xmb's picture

As found by machman Maplin have an offer on a suitable power supply for £12.99 (until 23/01/07), so UK owners have a cheap solution!

http://www.maplin.co.uk/Module.aspx?M...

The output voltage can be selected by a switch to give the required 7.5V and it can supply up to 3.6A, so more than staisfies the RS Media requirement of 3.1A.

Just make sure you set the tip polarity correctly!

Hunter
Hunter's picture

xmb, thats the one im going for, at that price you can't go wrong.

machman
machman's picture

xmb, I like the recharge solution you offer.

Gaza how long did it take you to type that out? A cracking insight into how to solve the battery problem, not something I would be brave enough to have a go at tho. Still you can proudly announce that you have the 1st RSM with feet warmers. ;0)

Gaza
Gaza's picture

Didn't take as long to type as it did to figure it out. The kids made him sit up this-afternoon and I noticed his feet came off the floor for a bit so he might get some lead in his toes yet.

Trying to decide on the next 'Pimp my bot' project. Clock, thermometer and quality-of-life read-outs are contenders.

BigKid
BigKid's picture

Well I bought an RS Media and got the Dick smith power pack (recommended by Nocturnal) which works well. Unfortunately batteries have been a major pain. Originally I got the NiMH D batteries Gaza talked about, while they supplied plenty of power they are way to light and RS can't sit/stand or low pickup without falling over, also when walking he looked drunk (which was kinda funny!). I then tried some standard DS alkaline (non-rechargable) batteries that they have been selling with the robot, I managed to get him to lie down/sit/stand up a couple of times then he was too flat to walk so I took them back and got my money back. I have now exchanged the NiMH batteries for the NiCd batteries which are considerably heavier, have too wait a couple of days for them to charge now. Sounds like Gaza is getting reasonable results with these..heres hoping :-) Also watch out for the DS rechargable AA batteries, these were fine for the controller but are slightly bigger than standard AA's and get stuck when put in RS's feet, didn't seem to make contact & were very difficult to get out.

Slightly off topic - The LCD screen quality is terrible, photos (not taken by RS) of people look whited out (over contrasted) is the any way to change this? Has any one else noticed this or could mine be faulty? Same photos look surpurb on my cellphone. 

Gaza
Gaza's picture

Bigkid, I don't know where I saw it now but there is a note on one off the boards about adding spacers, small washers will do, under the outside plastic 'bumps' on the bottom of Media's feet. I found that this helped to compensate for the lower weight, especially on carpet.

BigKid
BigKid's picture

Gazza, finally got to have a decent play tonight (2 weeks since I purchased him!) The Yellow DS NiCds seem to be doing the trick, he can sit up and stand up without assistance and perform low pickups. He only fell over once and that was my own bodycon, think he performed a thrust while leaning fwd and fell on his face! Anyway much happier now, how long do your batteries last? Also do you know of any D battery chargers that can charge the NiCD's faster than 48 Hrs (currently have DS one)?

 I am using him on carpet, seemed to go well, turning was very slow though, seemed to be a lot of movement for not much turn - do you think  the spacers may help with this? 

 

BigKid
BigKid's picture

Arrrh - My battery probs continue, the NiCads only lasted for approx two hours of running, 2nite he was too flat to walk when my Nephew came round  - poor little guy, its the third time I've tried to show him the robot and its died. Gazza how long do your yellow DS NiCads last? I'm now thinking about returning the bot as 4 days charging for 2 hours running time is hopeless. Bummer as I like the robot when its going.

Gaza
Gaza's picture

My batteries last long enough as the bot spends more time in pieces with a probe up his nose than what he does doing much else. I modified him so I could plug a charger into his foot and charge all batteries at once without taking them out. With the power pack I had on hand that takes 24hrs. A bigger power-pack, 450mA and a modified charging circuit and he would be done in 16hrs (at the batteries recommended standard charge rate). An even bigger pack, 600mA and he could do a fast charge in 12hrs.

Two hours does sound a little low though. These are 4500mAh batteries. To flatten them in 2hrs you need to be drawing 2.25A continous which is lot! Standing still he draws around 300mA; lifting an arm takes it up to around 500mA. I don't know what the walking current is. Maybe your batteries are not fully charged?

BigKid
BigKid's picture

I'm charging them again, I only have the DS charger which recommends 48 Hrs for 4000mAh so 54 hours should do 4500 mAh, unfortunately I just have the one charger so I have to go through this twice, hence the frustration. Does your charging set up charge both the D's & AA's in his feet. I have the 7.5v, 3amp DS power pack, how hard would it be to modify RSM to have that charge his batteries and how long would it take. Would that mean you need to remove the batteries once charged if you want to continue using mains power? My electrial knowlege is limited as you can probably tell Wink

BigKid
BigKid's picture

Gaza, one more thing, I did try DS alkalines (sliver ones - they sell then in a package with the bot) and these drained in minutes (struggled to lay down and get up twice - then too flat to walk)  - are they hopeless batteries or could there be a fault in the bot causing rapid battery drain? 

Hunter
Hunter's picture

I just want to double check that the AC adaptor that i got is ok for my RS Media it has 7 output voltages- 5,6,7.5,9,12,13.5 and 15Vdc which i have it set on 7.5V

it is rated at 5000mA which im lead to believe is the max power that the unit can supply, the RS manual say's 3.1 Amperes so as its below 5000mA of the adaptor it can easily supply the power.

Is that right?

Thanks

Hunter.

BigKid
BigKid's picture

Hi Hunter

The one I bought sounds similar, it also has selectable voltage (with 7.5 option)  but it only supplies up to 3.0 Amp. Works perfectly though. Came with multiple connectors and one of them fitted RS Media, just make sure you connect the connectors right way round so its "centre postitive" as per the manual.

Hunter
Hunter's picture

Thanks for the reply i just was not sure about the 5000mA bit and did not want to fry his brainLaughing

As you say check the plug is round the right way, i almost made that mistake, easy to do when you are in a rush to get him up and running.

Hunter.

quantumandy
quantumandy's picture

Hay Big Kid, were & how & who can I get one from. I read and re read all your listings and are having the same frustrations.. Please Mail me on andy at headline dot co . our country... please need ya help and don’t want to re -invent the wheel. Any help would be just superb Regardsme

 

quantumandy
quantumandy's picture

Hay Big kid. Dicky Smiths do have them they are just idiots. they are about 60$ and do from 1.5 to 12V. including 7.5V and it works a treat!. if you still need it mail me at quantumandy@hotmail and ill geta part no for you

quantumandy
quantumandy's picture

nevermind just read your last post

Zappatrax
Zappatrax's picture

What type of adapter can I use for 1? People are saying it's a pretty stock part and that you can get it in a lot of department stores, but I don't know what to look for! Please help! And does the AC adapter charge it or connect it to a PC?

StunningD
StunningD's picture

Here is where I got my AC/DC adapter for my RS Media and it works great :-) They have many, many adapters.

 

http://www.powerstream.com/ac-07503.htm

 

And oh, if you would have searched for a thread I posted the one that lists this same link :-)

http://www.robocommunity.com/forum/thread/17174/Found-AC-DC-Adapter-@-reasonable/