ROV controlling motors

Mintlawrov

Kids in my school are building an ROV for a competition, they have 6 pumps which are 12v 5 amp Johnson pumps.

They are using 3 stamp boards (the module based, red ones which are used in secondary schools) each one controlling two motors. They plan to connect a 12 volt supply to the external input on the output module.


The problem I am facing is whether or not the output module will manage to power the motors which are obviously running at a higher amps and higher voltage.

Can any one help???

Thanks

Duane Degn

Mintlawrov wrote: »

They are using 3 stamp boards (the module based, red ones which are used in secondary schools) each one controlling two motors. They plan to connect a 12 volt supply to the external input on the output module.

I didn't see any red boards listed under "Basic Stamp Boards".

I'm pretty sure 5 Amps at 12V is more than most boards can directly output. You'll need a relay or some sort of high power transistor in order to control that much power from a Stamp.

Here's a link to a thread discussing using a Stamp to turn things on and off.

Mintlawrov

http://www.techsupplies.co.uk/epages/Store.sf/en_GB/?ObjectPath=/Shops/Store.TechSupplies/Products/BAS110


Thanks, that was my worry!!!!!!

Link above is the stamp boards we use, there isan image of the input module below, the output module is the same.

Thanks

Ali

Duane Degn

Mintlawrov wrote: »

http://www.techsupplies.co.uk/epages/Store.sf/en_GB/?ObjectPath=/Shops/Store.TechSupplies/Products/BAS110


Thanks, that was my worry!!!!!!

Link above is the stamp boards we use, there isan image of the input module below, the output module is the same.

Thanks

Ali

Is this the output module?

http://www.techsupplies.co.uk/epages/Store.sf/en_GB/?ObjectPath=/Shops/Store.TechSupplies/Products/BAS119

If so, it looks like it uses a Darlington array. I'm pretty sure both the "Stamp" board and the modules are not Parallax products.

I haven't used Darlington arrays much myself but I don't think they can handle the current you need. You could use the Darlington output module to control relays to turn the high current motors on and off. This would eliminate the need for a driving transistor. You'd still want to use a diode across each of the relay's coil.

Parallax sells relays that may work for this project but I couldn't find any appropriate diodes in their store. Parallax uses 1N4004 diodes in their Dual Relay Board but they don't sell the diodes individually. The relays they sell require 12V to activate them. I don't know what the voltage output is on the output module you're using. You many need to find an alternate source for relays.

If you wanted a quick solution you could use the Dual Relay Board I mentioned earlier.

Prophead100

On a similar ROV project, I found it easiest to use a set of socketed 12 V powered relays run by transistors switched on by Stamp pins through a resistor. The relays can purchased cheaply and are replaceable. Its also nice to see the physical operation during testing. A diode across the relay protected the circuit although another across the transistor would be better.

Mintlawrov

Yes that is the output modue, that was my worry, im a bit of a novice with the stamp controller, can teach the basics but the advanced electronics is a bit frustrating.....

Thank you for all your comments, I'll investigate all the solutions and get back to you.

I'm beginning to consider ditching the stamp board and work manual toggle switches.

Needs to be sea worthy in 6 weeks!!!!

Thanks