Hobbs Meter
Hobbs Meter
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Here are links to two articles about adding Hobbs Meters
Plus adding Strobe Lights for the rotax engine.
An alternative to the hobbs meter is the "Tiny-Tach" which is an internally powered tach and hour meter. It is a little more expensive than a hobbs meter and it only operates when the engine is running. It is marginal as an accurate tach in my opinion but the hour meter function is hard to beat. I also purchased a copy of the "TinyTach" a few months ago on eBay and it is called "SenDEC". The SenDEC functions are identical to the Tiny-Tach. I believe that I paid under $15.00. If you were to go with the Tiny-Tach / SenDEC route, you need to specify for 2 stroke because the pickup works off of the spark plug and they are made either for 2 or 4 stroke engines. I have 2 tiny tachs which I bought in 2001 originally for a powered parachute and they are still running fine.
This is probably old news to you about the tiny tach but it may be of use for someone just starting a build.
AND NOW, HOPEFULLY, THE ANSWER YOU WERE LOOKING FOR:
http://www.800-airwolf.com/pdffiles/ARTICLES/part33.pdf
Quotes from the above Airwolf PDF File:
"Hourmeters: To the best of my knowledge there is currently no hourmeter that will work off A/C voltage only. All hourmeters require from 4 to 40 volts
D/C to operate. It says so clearly on the hourmeter instructions. Yet the number of people that will hook them directly to the lighting coil staggers the
imagination! This indicates to me they simple do not understand what the engine's lighting coil is producing and hopefully we are taking care of this with
part #33. What you do have going for you is the fact that the voltage range that most units will work in is fairly large (4 to 40 volts). Using the #9251
regulator allows you to run an hourmeter with the only drawback being the possibility of not having enough voltage available at idle to get a reading.
Any RPM higher than idle and enough D/C voltage will be available. There is some discussion on where or not the 1 amp minimum load required by the
#9103 is satisfied by an hourmeter. My suggestion is to use a capacitor or charge a battery as outlined earlier of best results."
"Full Wave Bridge Rectifier: An interesting piece showed up in the February '92 issue of
Ultralight Flying! Magazine suggesting an inexpensive Hobbs connection with a full wave
bridge rectifier. Using a
Radio Shack part #276-1171, costing around $2, A/C lighting coil
voltage is transformed into D/C. Figure #6 shows a simple schematic on this part. Being a
little skeptical, I contacted Westberg Mfg. for their comment on what looks like a great short
cut to an A/C driven hourmeter. They stated that this type of system would not work with
their hourmeters. This leads me to believe that Hobbs hourmeters and Westberg
hourmeters are configured differently and should be treated as such. Westberg tells me
that an A/C hourmeter is in the works and should be available sometime in the future."
http://www.800-airwolf.com/pdffiles/ARTICLES/Part 49 - 4 page.pdf Info about regulators you may be using.
And another alternative is the "Kuntzleman Hot Box". The auction has ended but you can read about it for your info.
http://cgi.ebay.com/ebaymotors/NEW-...003QQitemZ130138598154QQrdZ1QQsspagenameZWDVW Notice which regulator is attached to the Hot Box - DC power for hobbs meter.
P.S. the ebay link is not me, was just cruising eBay for anything aircraft several days ago.
Hope this helps