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  #21  
Old 01-30-2016, 07:13 PM
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FresnoR FresnoR is offline
 
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I am going to drift a little beyond the intercom. Have you thought about what it would take to design a 2.25" electronic directional indicator with an LCD screen? Obviously it wouldn't be gyro driven, but using the sensors that all of our phones use for their compass.

There are no other companies that make something like that and I think it would be really slick, and rather simple.
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  #22  
Old 01-30-2016, 08:23 PM
CATPart CATPart is offline
 
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Quote:
Originally Posted by FresnoR View Post
I am going to drift a little beyond the intercom. Have you thought about what it would take to design a 2.25" electronic directional indicator with an LCD screen? Obviously it wouldn't be gyro driven, but using the sensors that all of our phones use for their compass.

There are no other companies that make something like that and I think it would be really slick, and rather simple.
Here is a link I have had bookmarked for a while, lots of cool ideas, though maybe a bit old school. He has a digital compass, just not 2.25"
DIY Avionics: http://lea.hamradio.si/~s53mv/avionics/avionics.html
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  #23  
Old 02-05-2016, 06:52 PM
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vlittle vlittle is offline
 
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All of the mixer amps and stereo music adapters that I developed for aviation use had the capability of high fidelity (20 Hz-20 KHz +/- 1db, low THD). Simply by using the right Opamp, great improvements can be made while reducing cost. For example, the TLC082 opamp and related devices are almost ideal for this application. The only exception is that they are intolerant of overvoltage on the power supply, so good regulation is essential.

One could redesign the RST audio panel using these devices and achieve excellent results.

However, there is a rule of thumb that I learned 35 years ago while I was a designer at Mitel. Take your parts cost and multiply by four. That's an estimate of what your average selling price has to be. Anything less and you can't make money. The things I designed sold in the millions of units (telephone line circuits).

At lower volumes, you have to make more. At PMC-Sierra, we would not look at building a device that only had 75% gross margins. 75% gross margins are what furniture manufacturers make, with no R&D budget.

So it's fun to do and great for the community, but don't give up your day job!
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  #24  
Old 02-06-2016, 12:38 PM
Radioflyer Radioflyer is offline
 
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Location: Boston
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I purchased a homebuilt with a great suite of king avionics but soon found out that all the audios were simply wire twisted together. What a mess. I too couldn't believe the prices on factory audio panels. So, I whipped up a simple, but proper panel using one of the available 8 channel audio mixers. Alltogether, about $150. Basic and works ok.

As a new feature, it would be nice to have voice synthesized capability that can be triggered by something like a canopy open microswitch, etc.

BTW, I encourage this grassroots development effort. Screw the legal bull. This is amateur, diy stuff, use at your own risk, and you aren't looking to be truly commercial.
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  #25  
Old 12-29-2017, 03:41 AM
rv8ch rv8ch is offline
 
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Default Any progress?

Just curious if you have made any progress on this project? Sounds really interesting.
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  #26  
Old 12-29-2017, 02:12 PM
lr172 lr172 is offline
 
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Location: Schaumburg, IL
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Originally Posted by BCP Boys View Post
I'm right there with you on getting my head wrapped around the cost. I can understand the fully featured ones that have stereo 3D sound separation, VOX and other "cool" features. But for $2000, that's just a lot of money for these features, especially for a 2 place experimental. I have to admit, my audio panel is made of 3 standard switches :
Switch 1- Two place switch to TX between Com 1 or Com 2
Switch 2 - Three place switch to RX between Com 1, Com 2 and Both
Switch 3 - Two place switch to RX Nav 1 or Nav 2

Now this isn't perfect but it allows me to listen to 2 frequencies at once and switch between the 2 Coms or Navs at a flick of a switch.

Cost? approximately $15. Does it work? You betcha.
Is it cool and have nice features? Not a chance
I did something similar. I got a PM3000 on ebay for $100. I then used switches. I have a Com 1 / Com 2 switch and a 3 throw switch that connects one of the unswitched (and un-muted) inputs between my offline Com (Com switch routes the un-selected comm on this feed), Nav audio and GPS audio. The EFIS gets the other unswitched. Paid an additional $15 in switches (require a 4PDT and 2P3T / On-On-On). This seems to cover my needs well.

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Last edited by lr172 : 12-29-2017 at 02:16 PM.
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  #27  
Old 12-29-2017, 02:20 PM
lr172 lr172 is offline
 
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Location: Schaumburg, IL
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Quote:
Originally Posted by vlittle View Post
All of the mixer amps and stereo music adapters that I developed for aviation use had the capability of high fidelity (20 Hz-20 KHz +/- 1db, low THD). Simply by using the right Opamp, great improvements can be made while reducing cost. For example, the TLC082 opamp and related devices are almost ideal for this application. The only exception is that they are intolerant of overvoltage on the power supply, so good regulation is essential.

One could redesign the RST audio panel using these devices and achieve excellent results.

However, there is a rule of thumb that I learned 35 years ago while I was a designer at Mitel. Take your parts cost and multiply by four. That's an estimate of what your average selling price has to be. Anything less and you can't make money. The things I designed sold in the millions of units (telephone line circuits).

At lower volumes, you have to make more. At PMC-Sierra, we would not look at building a device that only had 75% gross margins. 75% gross margins are what furniture manufacturers make, with no R&D budget.

So it's fun to do and great for the community, but don't give up your day job!
A small world. I sold PBX's early in my career and once worked for a Mitel distributor.
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