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Ezb V4 Power Shield , 5 Volt, 6V, 7.4V , What Do You Want?

Hello Everyone , I had this idea when the v3 was around , but I wanted to wait until v4 was in circulation before pursuing it. The concept is a shield that plugs in directly on top of the existing EZB v4. It would regulate 5 volts on the power pins. Then of course I was thinking... WAIT! 5 volts is a fine standard, but servos run on 6 volts by standard and some high torque get the most power with 7.4 volts! So there are some options. I want to make this shield generally available to the community for testers. I imagine two or maybe three different versions of the shield would be appropriate.

1. 5 volt standard servo shield- all 24 digital power pins regulated by a switching psu , green certified , Gold standard efficiency 96%

2. 5 volt @7.5amp with switch to 6 volt @ 10amp Boost for High Torque servos, preset for all 24 digital power pins , switching psu, green certified, Gold standard efficiency 96%

3. Dynamixel shield option - 5v @5a and secondary power option 12v @10a continous.

The switching regulators cost more however they produce less heat and waste less power. This increases battery life of your project.

what I would like is feedback on is how I should lay this out. How do YOU as a user want the shield.

1 Top mount pins line on v4 now or 90 degree out to the sides?

2 dip switches or physical jumpers to change voltage from 5 volt to 6 volts (or 7.4 if your servos can take this continuously )

3 what battery voltages does everyone use, I want to configure shield for most users so they do not need to use a plether of step down converters.

4 whats your idea or opinion , lets be constructive afterall I am doing this for you :)

#6  
@RB550, Yes that's true ! It would prevent the accidental damage of sensors when you plug them in and realize.... oops , " I just let the magic smoke out of that 30 dollar maxbotics sensor I just bought!" It's really an inevitable mistake.

@Alan , I am reading over data sheets till my eyeballs hurt to find switches that small that can also handle 1 amp + current to run through them. The dip switches I have seen so far are 25ma to 200 ma which is fine for a LED light but not a servo. So either a larger switch or jumpers may be the answer.
United Kingdom
#7  
But would it prevent accidental damage? If the shield is set for 6v or 7.2v and a 5v sensor is plugged in it would still smoke.

The switch may not need to handle the full load current. Transistors may be able to be used to allow a small switch be able to enable a large load. Think about the principals used in the TIP120/TIP122 circuits.
#8  
@Rich , If the shield came preset to 5 volts then yes it would prevent the damage , someone would have to change it then plug in the sensor to the 6 volt output. All scenarios to prevent damage cannot be prevented, but as a experiment I let 5 people try to set up a basic radar test and motion detector. This is after after watching some tutorial videos to show how easy it is and all forgot that the voltage would damage the ultrasonic and motion detector modules we were using. I recorded it but didn't post because... well that was embarrassing lol. I bought a pack of ten sr04 , so I was prepared for a magic smoke party. Lol
#9  
I pointed out I could make a ALL 5 volt shield and then a alternate shield for the ezb pros , with servo boost voltage. The 5 volt may really be best for the beginners to ez robot or electronics in general.
#10  
Jumpers instead of switches wouldn't prevent a sale, they are just a personal preference. If you can't find something suitable, I wouldn't complicate the design with transistors just to make switches work.

Alan
United Kingdom
#11  
Why complicate anything with switches or jumpers?

It seems the general view is smaller shields for banks of ports to limit voltage so why not have totally separate boards, one for 5V, one for 6V and one for 7.2V? Colour coded could be an option too since you can pick circuit board colour these days, red for one, yellow for another, green for another and so on.

A 6 port (or however they are split on the EZ-B) voltage regulated shield would go down a storm. Pass through the signal and the ground, regulated Vcc to 5, 6 and 7.2 volts, plug in and away it goes.

I was playing with designing a voltage regulated board for the V3, to allow external power and regulate it. My board was pretty large as it was built with Melvin in mind but it wasn't complicated. Vin to the regulator, Vout to the power pins of the new digital ports, a couple of capacitors, resistor and LED, common ground, the signal was the only tricky bit as they need to all be separate but with a 2 layer board it's not difficult to work out. It never happened as the V4 was announced shortly after but I am sure it would be something the community would love.
#12  
Ok , so I suppose if you were using a 7.4 volt board just as a example but then needed to hookup three sensors , then use 3 inline voltage regs to drop it to 5 volt. That's your suggestion right?
United Kingdom
#13  
No. If you have 5v sensors to use then you would use a 5v board. If you have 6v servos use a 6v board etc.

Inline regulators (like the 5v one in the shop) are great for one sensor but if you plan to use say 3 ping sensors (front, left & right) then a 6 port regulator shield would be perfect for that. Or if you need to drive 2 arms with 3 servos per arm at 6v then a 6v shield would be perfect.

The design of each board would be identical, just the components would differ (and the colour possibly).
#14  
I had the same thought as @Rich... have colour coded banks or mini shields that only fit 4 pin banks on the ezb... yellow for 5V, green for 6V, and blue for 7.4v... or something like that....
#16  
Ok so 27.99 cost to power 8 servos and it doesn't include any king of regulator , so the reg is a seperate cost.
#17  
Don't get me wrong I know this could be made way cheaper than $27.99 assembled or $17.99 un-assembled! its a good proof of concept for making dedicated boards though. it would be perfect if the regulator was built in or was already inline with the power source wires like the regulator from ez-robot
United Kingdom
#18  
Isn't half the idea of a shield to avoid having all of those flying leads?

Seems very pricey for what it is too.

Here's an early version of the power board I was working on (I don't have the latest one here as it's at work but you get the idea of it's simplicity)

User-inserted image


It wouldn't take much at all to convert it to a shield for the EZ-B. You have your simple in and out for Vcc, Ground and pass through the signal.
#19  
@Rich... I know you don't want to step on ez robot's toes or anything, but are you in the position to have these things made for sale? Right of the bat I would buy 10 of each 5V, 6V and 7.4v.... Provided I got the Rich/EZ Robot discount of course....:D
United Kingdom
#20  
It's not in any kind of position to be sold, it's never been built or tested and was abandoned about a year ago.

If I get chance and remember I will send my designs I have at work home tomorrow and play around a little more and gladly share the ExpressPCB files (from which you can get the boards made or adjust to better suit your plans)
#21  
@Rich... No worries. I do see a market for "these" mini shields so hopefully EZ Robot or someone will produce some...


Cheers
Richard
#22  
Can I print directly from express pcb? In order to etch pcb?
United Kingdom
#23  
It's not really where my expertise lies (it's been 17 years since I was at college doing this stuff - which makes me feel old!).

Although I posted my first version/concept for inspiration to Josh and would have no issues with anyone building off of it (I'll re-add it to my list too). This looks like it could be a useful and cost effective regulator which would work with some minor changes to the layout of the board, plus it's adjustable too which solves the whole "what voltage?" question. However it's not as efficient as the switching regulators. But for an initial concept/idea it's something to build off of.

I'm sure Jeremie is cringing at my crude attempt *blush*
United Kingdom
#24  
@Josh, there are various print options in Express PCB plus various "export" options. However it is free and offered by a company that's main business is PCB production so my guess is it's likely to be pretty limited.

I only use it as it's free and I can get a rough concept out. If I was to do it properly I would use something else such as Eagle. There are many better programs than Express PCB for this.
#25  
I think that there should be essentially "Micro Shields".

If you look at the ez-bs digital ports, there divided into groups of 4. Why not make a mini shield that uses the same concept? This micro shield could clip right in place, would not interrupt other ports, and could have a exchangable regulator, so you can have the voltage you want at an amperage you need. As well, you can regulate the ports you want and don't want. Plus they would be fairly easy to manufacture.

User-inserted image


Just my take on it though.
:D