DC motor + gearbox + encoder + PID - Page 1
Forum section: electronics / beginners

author: MuTeD
author_rank: Contributor
timestamp: November 24, 2014, 01:39:05 pm
content: Hi,I want to control a DC motor and cannot use an ordinary servo because I need to be able to turn more than 180 degrees. Furthermore I like the modularity that the DC + gearbox + encoder + PID solution offers. The problem at this time seems to be the price that this comes at, it is a lot more than I expected. Currently I'm looking at the following pieces:DC motor: $3.19http://www.digikey.com/product-detail/en/PPN7PA12C1/P14355-ND/2417079Gearbox: about $30.00http://be.farnell.com/maxon-motor/110483/gearhead-spur-64-1-ratio/dp/1761288Encoder: $23.63http://www.digikey.com/product-detail/en/AMT103-V%20KIT/102-1308-ND/827016This comes in at a total of about $60 for roughly the cheapest I could find. I didn't even look at specific specs or anything like that yet. This is far more than for example this integrated solution:http://www.robotshop.com/en/12v-gear-motor-encoder.html.So basically my question is, Is this to be expected that doing this yourself is far more expensive than just buying an integrated solution or is there something I'm not understanding? Granted the integrated solution might be of lesser quality. Is this modular approach what is generally used in the industry? Are there any (better) alternatives? Thanks!Kenny

author: Kjelt
author_rank: Super Contributor
timestamp: November 24, 2014, 02:51:23 pm
content: Quote from: MuTeD on November 24, 2014, 01:39:05 pmProbably looking in the wrong places, at Farnell you get the BMW of stuff, if you look as comparison for a chingchong from robotshop than you should look for chingchong parts at Ebay and sorts.For instance just two second search a motor and gearbox $8http://www.ebay.com/itm/12V-DC-3-5-RPM-High-Torque-Gear-Box-Electric-Motor-New-/360519569444?pt=LH_DefaultDomain_0&hash=item53f0a41024

author: MuTeD
author_rank: Contributor
timestamp: November 24, 2014, 03:02:11 pm
content: Well thats why I said that I expected the integrated one to be of lesser quality =).I'm just kind of surprised at the price of the modular approach because what I'm doing is basically just a servo that can rotate more than 180 degrees... But I assume that this modular approach is the way it is usually done.

author: free_electron
author_rank: Super Contributor
timestamp: November 24, 2014, 03:03:09 pm
content: plenty of full turn servo's around on ebay. for like 4$

author: MuTeD
author_rank: Contributor
timestamp: November 24, 2014, 03:19:57 pm
content: Quote from: free_electron on November 24, 2014, 03:03:09 pmThanks for the info but I don't have a problem finding cheapy ones. I was just wondering if $60 is pretty much the least I can expect to pay if I go this route (judging from Kjelt's reply, the answer seems to be yes) and if this was the "standard/good" solution.

author: Kjelt
author_rank: Super Contributor
timestamp: November 24, 2014, 03:37:42 pm
content: Well that was not my intention. My intention was to tell you that you compare a product from a robottech site which has probably sources from the far east and less overhead (small startup) to a digikey and farnell which have a big overhead, deliver to other companies that demand quality so their source are other companies that have quality assurance etc. etc. could also be from the far east but then are certified etc.So my intention was to tell you that if you want to compare a finished product with parts 1+2+3 to single parts 1, 2, 3 you should look at the same supplier for the four items. Than you probably will not be that far off in price (probably 20%)