While looking for a Micro 75 Mhz receiver, I came across a robot site with many interesting products applicable to our Footy Class boats… Size and weight being an issue I am looking for the best combo electronics package to do the job with minimal weight…
The Micro receiver looks good and claims to have a 1500’ range which is important… The range on the Nano might be too short at 300’ to allow for reliable control… Micro servos at 6 grams and Deans base loaded antennas could help make for a minimal package…
soon. i’m waiting for my sail servo.
i’m gonna paint it this week.
messing with rig right now.
pics will follow soon.
LOTS of micro carbon bits…tiller, pushrod, radio plate, micro servo horns, etc.
just picked up some micro spectra for lines.
got new reinforcement inventory and was itchin to use it.
they say there is a global shortage of “A” class composites…not in my shop!
The hook up is the same as any receiver servo setup… I use Berg receivers on 72 Mhz that are the same size or smaller… The servos plug into the pins on the one end, and a very small crystal plugs into the other… Battery is piped in through any one of the unused channels…
This is one of the first truly miniature 75 Mhz receivers that I have seen available… I am tempted to try one of my Bergs on 75 Mhz and see if they are broad banded enough to use there…
I have attached a photo which shows the Berg a standard 4 cell AA pack a full size servo and an HS-55…
From the description on that link, it says, “Use a 75MHz single conversion crystal set that matches your Transnsmitter. (not included)” so it looks like you can use the crystal you got with your standard size radio.
But the confusing thing is, “Micro receivers are Not programed for use with 2 and 3 channel transmitters.” Do you need a special transmitter? That sounds like it won’t work with the 2-channel transmitters most people use for sailing. I have a 4-channel Ffutaba that I use for my sailboats, so it looks like that would work.
They are the type of modulation the transmitter uses and the receiver must match that modulation… Most older or low end radios use AM… FM is in use by most aircraft ( 72 Mhz ) radios as well as higher end surface ( 75 Mhz ) radios… I will leave the new 2.4 Ghz stuff out of the discussion…
PPM vs PCM
This is the way the transmitter sends the proportional control logic to the receiver and again must be matched by the receiver… Again only the high end FM units have PCM as their encoding method… Most FM units use PPM encoding… The Micro Receiver we are looking at does PPM so would be compatible with most FM transmitters by the major radio makers…
Example radio would be say the HiTec Laser 4 which is available on 75 Mhz… It is a two stick unit and a complete system with receiver and two servos is around $120… From my experience, a sailboat is best controlled using a 2 stick transmitter… This allows you to set up the ratcheted throttle control on the left side as your sail trim control and then use your right stick for rudder… A pistol grip type controller as used for cars, is great for a fast electric hydro type boat, but very uncomfortable for me to use on a sailboat set up…
One final thought is the crystal (xtal) needed for the receiver… The one we are looking at in this thread is a single conversion receiver and thus needs a single conversion crystal… Many receivers are double conversion and would require a double conversion crystal…
Hope this clears up some of your questions… Take care and have fun…
I use a pistol transmitter for about any boat I have. You just need to get used to it. I also prefer a 4-channel transmitter to a 2-hannel one because it’s much simpler to operate the boat than using 2 sticks.
Some examples of FM transmitters ywould be helpful so you know what to look for on eBay.
I use the HiTec Laser4 which is an FM dual-conversion set. Do you know if a single-conversion crystal and the micro receiver would work with this transmitter? I’m afraid I’m better at building boats than understanding the electronics!
Futaba and Castle Creations both have new micro recievers out.They were either 4 or 6 channel FM units. Check TowerHobbies for micros.
The only issue I see with receivers for Footy porpoises is that the BEC voltage regulator will put the servo’s voltage at 5.0 Volts, no matter what you use for a receiver pack ( usually up to 8.4V) which means the 4.8./V.6.0V torque ratings you see lited here or there are totally meaningless.
In the footys there should be no BEC as there is no ESC which is where the BEC lives unless you use a stand alone BEC… The receiver pack is 4.8v which is limited by the 4 AA cell rule… The battery connects directly to the receiver which also is the supply voltage for the servos… So, one needs to use the 4.8v torque specs… Normal RC receiver pack voltage is 4.8v not 8.4v The 6v servo voltage came about to provide more torque from the same servo… Go much beyond 6v and you will let the “Magic Smoke” out of many receivers…
The Castle receivers are Bergs and I will have to check but unless something new, they were only available on 72 Mhz… I hope they are making them for 75 Mhz as the Berg/Castle is a great receiver… I have used them for several years in RC aircraft… The receiver in my previous post on this thread is a Berg 4 channel… Take care and have fun…
Bruce, you need to get up to date on ESCs and BEC receivers.
First of all, you don’t need an ESC to get a battery eliminator circuit in your radio system. The purpose of the ESC’s battery eliminator circuitry is to allow you to use the mains 7.2 to 38 Volt battery pack ( like in an electric car, boat, or airplane) to deliver the 4.8 volts ( or whatever the documentation says) to the receiver.
Second, Just about all the newer receivers have BEC bcircuitry. You can hook up ANY receiver pack, up to 8.4Volts! (again read the documentation for your receiver) and the receiver’s BEC stuff will reduce it to a regulated 5.0 or 5.4 volts, acording to the design. On an aside, some r/c fast electric boat people use a 9Volt battery for the receiver & rudder servo, to save weight. Some CMOS-based receivers will handle a 9V battery, and can go up to 15! volts, but is not recommended for most people to do. Regardless of what voltage battery pack you use, the receiver’s BEC circuitry will regulate it.
Third, only a 4-cell NiCd or NiMH battery pack will give you 4.8 volts. If you use 4 x AA alkalines, you will have a 6.0 Volt battery pack, and combinations of Li-Po cells can give you 6.0 volts. Again, the receiver’s BEC circuitry will regulate the power TO THE SERVOS at about 5.0 - 5.4 Volts, according to the the specs. So there is no way you can get 6.0 volts to the servos, through a BEC receiver, unless you bypass the receiver’s BEC circuitry totally, or you have some kind of oddball receiver with a different BEC circuit or none at all, or are using some kind of a Y-harness, which feeds the unregulated power straight from a 6V battery.
I have not seen any documentation on the Berg-design receivers. I presume there is no voltage regulator, to save weight & size, so you are on your own there. Since Castle makes a lot of ESCs and things for boats and cars, it’s possible that they will have 75MHz receivers available sometime. Everybody should call them and request it. The URL is: www.castlecreations.com
Dual conversion applies only to the receiver and receiver crystal. it is used to combat co-channel interference (aka the 23 channel problem. For long boring technical reasons, single conversion R/C receivers can be interfered with by a transmitter that is on a frequency 23 channels away. For example, a transmitter on ch 61 can interfere with a receiver on channel 84 or vice versa. There are only 7 pairs of frequencies so affected, 61-68, and 84-90)
As long as the transmitter and receiver are on the same frequency, or channel, it matters not whether the receiver is single or dual conversion.
What better to handle two sheets, a tiller, and the nav computer?