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I would avoid M.Lishman. I had a meter serviced there last year, used it for about 2 weeks during harvest, I opened it to replace the battery this year only to have a wire fall out of because of poor soldering.
I contact Lishman who tell me that shouldn’t happen but they dont have time to put solder the wire back on until after harvest. I have since phoned then and asked to speak to Gavin Lishman who I believe is now the manager. I was told he would ring back. Nothing has been heard from him.
Hi wagstaf. It is worth considering the Dickey John MiniGAC. Its a whole grain tester with adjustable calibrations. Its build quality is far superior to the Sinar. I have worked with Martin Lishman Ltd for many years and know the reputation for the Sinar is poor. If you would like a price on the MiniGAC, I would be more than happy to supply you a price.
If you are thinking of repairing or calibrating your Sinar, its worth sending it to Dry-It-Out in Leicester. Its cheaper than Sinar, and its where we send them at Lishmans.
Hello I’m a student Liverpool John Moores and I’m replying to your post because I believe you know the inner working of a grain moisture meter. For my final year project I’m trying to make a moister meter but i’m struggling to figure out how it works? I was thinking about using electodes to take measure the sample but i’m not sure how it works.
James, this thread is over a year old ! i doubt that many of us understand the inner workings of a moisture meter, I certainly don’t !
Presumably a small current is passed through the sample and conductivity or resistance is measured between the electrodes. How that translates to a moisture content would take several physics lessons to understand. If you are going to try and make one consider how the reading would vary betwen crop types and whole or ground samples.
You can easily make one, James Padget, if you need to.
The circuitry of the Marconi, and of some others, is a simple Wheatstone Bridge, named after the fertile physicist Sir Charles Wheatstone (1802-1875).
As you will know, a Wheatstone Bridge determines the electrical resistance of a sample on test by noting the setting of a variable resistance (rheostat) when no current flows through the open bridge. Clearly, at this moment, the ratios of the voltages of the bridge’s two power sources exactly match the ratios of the said two resistances.
The voltages of the two power sources being known, the resistance of the sample can be read off the rheostat, moisture content as a known function of resistance being built into the conversion scale provided.
Clearly, the accuracy of this arrangement increases with the ratio of the voltages of the two power sources (45:1 in my Marconi). Hence the well-rehearsed difficulties posed by the requirement for power sources of one uncommonly high, and of one very much lower, voltage.
However, you could make a workable meter, albeit not a very accurate one, using, say, 12v and 6v power.