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Asked — Edited

Ez-B On/Off Switch

i thought about my wall-e... and thought...and thought... and one of the things i thought of was an on/off switch(painful to open up, close, open, close, etc.)
I decided to put a power button/switch on the power cable, the only thing is which one! Not sure what websit to go to or what voltage to buy it from.
Fine on connecting it. just need to know voltage and where.


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TOO bad i am not in your area,i dont drink beer it bad for you ,but still can buy me a drink of soda
I don't drink beer either, as a matter of fact. But I have my own soda maker! You're most welcome! You can find me on FB if you want.

BTW it seems that a transistor fixed the power issue I had with EZB shuting down while Rovio was docking. I'll let you know if it happens again, but it seems pretty stable now. I made some research online and finally found some articles about induction. That was the magic word to know to find out what was causing this problem.

I ordered a power relay on amazon, even thought I still think of making my own switch using an OSFET, as you suggested me. I want to have my own circuit, of course, but the relay will be much easier. I found wifi enabled relays too, but it's damn expensive and, most of all, I don't know which one to chose! I found this here : http://www.controlanything.com/Relay/Relay/Wi-Fi_Relay_Controllers

I saved the link so I can come to this soon enough, but it will definitely drain too much power. I read somewhere that I could add more power to the EZB... I'll need to look into that... but it will add weight...:) the usual issues, I guess. I posted a video of my robot playing with my cats, it's there : http://www.youtube.com/watch?v=0rdwijq4Ldc

Thanks again,
RELAYS are not great for many reasons,one they use a lot of current to drive them,very slow switching,big in size and cost alot more then mosfets,

MOSFET thats about 37 amps is $.88 plus a resistor and diode for inductive load
Pk, I'll see how it goes then. I didn't know it would use much current. I'll go to radishak today and buy a mosfet. I guess I'll need a diode too. I tried to put a diode yesterday but it didn't give the expected result. But It was a diode randomly striped out from another device... Would you let me know what diode and mosfet I need ? Actually, just the diode because you already told me about the mosfet somewhere above.

Many thanks again.
United Kingdom
The diode and mosfet are detailed in the TIP120/122 tutorial

IRL3103PBF Mosfet

Although others can be used depending on the application.

Page 2 post 5 shows the other diode position for across the load rather than across the mosfet/transistor
IRLU024N IS A BETTER CHOICE for the mosfet its rated at 17 amps and at mouser like i said is $.88 SO ITS CHEAPER

MAIN reason is better is smaller package and then the price

ALSO EBAY HAS IT FOR 3 FOR $2.49 and free shipping

One i found about checking and testing mosfets that,that dont need a very high current mosfet ,like in robots that draw not high current 17 amps is still high for robot ,but size is very small
PLUS BIGGEST is cost compare to a mosfet at a higher current like IRL3103 AT $2.14 EACH

IRLU024N will take of any current or load needed on any robot design ,and dont need to have different current rating types

SECOND if you buy many like me its 25 at $.66 each

LAST time i bought IRL3103 WAS 25 at $1.67 each WITCH was needed for my H-BRIDGE design that needed 16 of them
elfege ,a good choice if going to radio shack is NTE2904 at $2.47

ALSO a diode is only needed for inductive load,i made a tutorial on this on and why
Inductive load is when driving a relay or a motor straight from the switch
SECOND the IN4001 is very low rated voltage and wont handle high voltage kickbacks from a motor or relay coil
Robotmaker, I've reread your explanation of why a transistor looses so much power and it can't be understood. I'm a little knowledgeable about such things and I can't follow it. When you get back from China and you find time in your new retirement schedule could you explain it more clearly and in simple terms?
United Kingdom
Fred, all components I've listed have been given by you in previous posts and topics. You are effectively arguing with yourself. If there are better than what I have listed in the clear and complete tutorial please bring them to attention explaining why and I may update the part numbers to suit in the tutorial. Everyone wants the most cost effective and efficient solutions along with as much information so that they make an informed decision based on their specific requirements, nobody cares who provides the information just so long as it's there.

I don't expect a clear and helpful reply but I may be proved wrong.
Ok can do that ,but its pretty simple ,measure the resistance of transistor emitter to collector is very high ,and then check the resistance on a mosfet its very very low like a switch .most are .1 ohm or less.

Just like ELFEGE said when he lost 1 volt ,i done tests long time ago when learning about mosfets witch i know alot about NOW and with my tests with a fully turn on transistor you lose more then 2 volts.

MOSFET is like a switch when its fully turn on.one main reason h-bridge designs now made uses them.

ZERO voltage drop
YES RICH that is what i did,try to give others a low cost idea and give very good detail as much as i can.

DONT need a tutorial to post info that is needed in other posts.

And i did make a tutorial ,but problems it had was hard for others to read or find useful info,because of the mess others made . but will make another one with photos of my design and a lot of info from web plus my info i have from mtesting mosfets that i dont many has done.

THIS info about the mosfet was for ELFEGE so it wasnt against you

ITS the same if i post a idea in other person post and you have a better idea you can post it too.

WE are all here it help others build robots ,LETS KEEP IT LIKE THAT please
OK, so its resistance that causes the voltage drop. The electricity is fighting to get to where it needs to go. Why is that, how come the voltage hits resistance inside a transistor and not a MOSFET? It sounds like a MOSFET is like you switch where it is fully on or fully off. But whats going on inside of a transistor?
ITEM about mosfets it uses 6 transistors to make the mosfet design ,plus low resistors and other parts.
here is very good info that compare both

One thing to keep in mind about Darlingtons is that, by their very nature,
there is a substantial voltage drop between the collector and emitter. This
causes more heat dissipation in the device, and results in less power to the
load. In some cases it is acceptable, in others it isn't. It may result in
the need for a heat sink, making it more expensive overall than a different
transistor which wouldn't need a heat sink under the same conditions.

I GUESS IT BETTER to find proof then try to explain it

here is the link that has a lot more info too

darlington transistor vs mosfets

I think on every post i made or reply too,its much easy to find info on the web for proof then try to explain it.

MAIN ITEMS I said about why a mosfet is better choice,low voltage drop across the collector to emitter,less power loss and no need for a heatsink

formula is in the link and they mention TIP120 AS A EXAMPLE
Thanks DAVE,going to use it in my tutorial on mosfets
It's really great to have you guys as advisers! I learn so much in so little time! I'm going to radio shack right now after a busy day.:)
ELEFEGE WE are all here to give good advice,and with your design you will help us in your ideas too.

Thats what i see great about this forum others helping others to make a good robot design
Hello guys ! Ok, well I think it is fair to say that I have done a good job thanks to your advices. I have a new question but first I want to let you know how my Hybride customized Rovio is doing : It works and safeties work too. I have overall 3 different batteries, one is kicking in automatically only if the two others fail and if this happens I have to quickly return the robot to its charging station because it's a 1amp battery and the robot might easily drain up to 6 amps, 5 for the EZ board + 3 for the rovio itself (it might share something like 1 amp with EZ board since its 3 amp battery is one of the safeties). It has a total of 3 cameras, one has night vision and can be controlled from iPhone, with a built in I/O switch that turns on/off the rovio. This camera itself is turned On/Off by the relay + transistor that I could set thanks to your advices (for some reasons I could never get the mofset to act as a switch... I gave up since I have largely enough amps to support a little 5v relay). NEW ! Today I installed an arm that I customized so the wrist can turn on itself. I'll post a video on youtube very soon so you'll be able to see whole thing at work, I just need to convince my wife to film it while I maneuver from my computer and my iphone. I still need to find out if there's a way to make a circuit that would prevent current from backdrafting into the rovio from EZB since its two main motors are still connected through both EZB and Original's Rovio controllers. and it really does not like it, I'm even surprised it didn't burn out yet!