Is there a stand-alone main/tail mixer board on the market?
08-14-2004, 12:44 PM
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RE: Is there a stand-alone main/tail mixer board on the market?
ORIGINAL: eheheh
Hi all,
anyone know if there is a stand-alone mixer board on the market that could mix main and tail signals?
Seems to be the missing link with the separates setups.
Most people seem to just let the HH gyro battle the torque to keep things straight and have the tail signal left mid way throughout all the throttle settings. Mixing on the tx is out of the question on the HH gyros so the only logical solution is to mix the throttle and gyro output signals and feed this into the tail ESC.
Anyone got a solution for this?
Perfect setup would to be able to measure the main rotor rpm and use this is the reference to mix with the gyro output to drive the tail ESC levels. Remove lag mixing issues that way.
Oi! GWS! there's an idea for the PHA-02! (oh, and throw in some sensible heat sinks)
Also, I noticed that there is a "Humming Board" that I assume the Hummingbird heli uses. Is this just a mixer or is it a combo ESC mixer for main and tail?
Hi all,
anyone know if there is a stand-alone mixer board on the market that could mix main and tail signals?
Seems to be the missing link with the separates setups.
Most people seem to just let the HH gyro battle the torque to keep things straight and have the tail signal left mid way throughout all the throttle settings. Mixing on the tx is out of the question on the HH gyros so the only logical solution is to mix the throttle and gyro output signals and feed this into the tail ESC.
Anyone got a solution for this?
Perfect setup would to be able to measure the main rotor rpm and use this is the reference to mix with the gyro output to drive the tail ESC levels. Remove lag mixing issues that way.
Oi! GWS! there's an idea for the PHA-02! (oh, and throw in some sensible heat sinks)
Also, I noticed that there is a "Humming Board" that I assume the Hummingbird heli uses. Is this just a mixer or is it a combo ESC mixer for main and tail?
http://groups.yahoo.com/group/microhelicopters/
look through the Photo folders under MIA Equipment and Mixers.
If you have not been there before, this is the where the Micro Helicopter "bible" started and a lot of the products there may still be available from MIA.
08-15-2004, 12:59 AM
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RE: Is there a stand-alone main/tail mixer board on the market?
Here are the initial results so far with using the TREC's mixing and using heading hold on the GY240:
Ended up putting a straightened paper clip with the end looped over through the center of the training skids link and then wedging the paper clip in between the two halves of the dining table so the heli wouldn't take off. Also moved the ping pong balls right up close to the skids so they could allow the heli to rotate easily.
Sat the laptop near it and hooked up the com cable to the TREC.
Spent an age trying to get the mixing to keep a steady tail through all the throttle levels. The duration it was taking me to get the throttle curve just right and the mixing gain right meant that the batteries kept draining down to the point that I would end up losing more and more power to the motor at set throttle positions. This in turn made it very tricky to get the curve right as I kept on over compensating as the power dropped.
Starting to think that I need an external power source (8.2V) to hook into the heli rather than constantly draining the batteries.
In the end I gave up and stuck with what I had ended up with on the throttle curve.
Gave that a quick fly without the GY240 AVCS HH mode on and the gain about 50%. Seemed quite stable mid hover but rotated a bit on the climb.
Then I turned on HH and had it's gain set to about 60%.
All seemed fine in a low hover...until I gave it more stick and then it started to oscillate the tail back and forth about 5 deg as it was climbing. It actually started to change heading slightly even though I wasn't moving the yaw stick left and right.
At this point I got the separate TREC gain controller and hooked it up to see if moving the mix gain on the TREC up and down by single increments made any difference. Well, it fixed the wag as I was climbing but I ended up throwing out the stability as I lowered the throttle. Even played with the GY240 gain levels to see if that could help.
At this point I realized that I need to put more of an effort into the throttle curve on the TREC...which I will get around to as soon as I can get a 25 amp power supply that has switchable voltage levels. Sick of draining the batteries.
In the meantime I figured that I may as well try switching off the mixer and play with the Advanced Options where I can feed the signal before the gyro into the TREC and it compares this with the gyro signal. It has acceleration / deceleration gain settings to help reduce the wag that you can get on HH gyro's.
That seemed reasonable in flight except for the constant small wag. Seemed to actually hold it's heading better than with the mixer on. Having the tail going when you haven't given it any throttle wasn't the best thing to be happening.
Then, out of interest, I grabbed my old PHA-01 all in one board and hooked up the GY240. Oh dear. The power for some reason was cycling off and on every second or so on both main and tail. Forget that idea.
So, at the end of a fun old day the mix-less setup yielded the better result all round. Given the wag-less condition of the tail at the low hover I suspect that if I can get the mix perfect in the first place across all throttle levels then I will have a far more stable HH.
Technical thought: on-board mixing is still floored as the throttle stick position will never always match the actual power / rpm produced in a consistent fashion due to the gradual drop in voltage from the battery. The main motor seems to be effected by this far more than the tail motor. As a result you end up with a mismatch even if you get the mix / throttle curve right at one voltage. That's the reason I feel a sensor to read the main rpm and use that as a reference for the mixer would be far more accurate. To tell the truth I think the best solution is to not have a separate electric motor for the tail in the first place.
Still, more setup and testing to be done to make things clearer on the subject. AND, the more people who give this a go the more accurate the conclusion.
Answers for Campbell Grant -
a) When the 3 to 4 pin adapter is connected between the main esc and the receiver, and the yellow auxiliary input wire is connected, does Mixing have to be enabled? And, if Mixing is disabled, must the yellow wire be disconnected.
ANSWER: Yes, the yellow wire is only used if you have the mixing enable OR if you are using the sampling option for the gyro signal (check latest 1.3 manual on this). Disconnecting it when mixing is disabled is not necessary.
b) In order to disable one of the BEC's, I have cut the middle servo lead on the TREC, i.e. I have only the two outer wires going to the gyro. Is this OK?.
ANSWER: That's fine but it may have been better to just slide the middle pin out of the connector and tape it up just in case you need it again in the future.
c) Am I correct in thinking that you do not need the mixing enabled? But, can it be beneficial to use mixing with a HH gyro.
ANSWER: I wish I could be definitive on the answer to this question but so far I haven't been able to get the mixing and throttle curve just right to tell you if it will be ok. At the points on the throttle curve with the mix is just right the heading hold has absolutely no wag so that in itself means that there is a good chance you could get it right. But at the end of the day if you dislike having to play with settings then a mix-less setup would be the go...provided you can get the gain on the HH gyro and the center position on the yaw channel just right in hover so that the tail doesn't wag. I had the TREC set to 72kHz but this didn't seem to make much difference to getting rid of the wag. More testing involved before I can be certain about all this.
d) In the instructions, under Advanced Gyro Settings, it details that you can use the 3 to 4 pin adapter between the gyro & the receiver, INSTEAD of between the main esc and the receiver. When is it advisable to use adapter between the gyro and the RX? Can I do this with my setup?
ANSWER: worth a try using this option when you are not using mixing. I gave it a quick go but haven't really had time yet to try different values. This option may very well be a good option to reduce tail wag. Let me know what results you have with this.
e) I.E. Is MIXING used when you do NOT have a HH gyro and ADVANCED GYRO CONTROLS used when you do have a HH gyro?
ANSWER: That's the general opinion going around at the moment but my objective is to see if a well set up on-board mixer will add benefit to a heading hold gyro.
f) I am also confused about the meaning of the “Main Throttle†in the “Controlling TREC from the computerâ€Â. I understand that the Mix Input is used to simulate the signal coming FROM the main motor, but I do not understand what is meant by: “The Main Throttle slider is the just like the prominent input to the ESC.“ Please can you clarify?
ANSWER: From what I can tell the left slider simulates the tail channel signal level (in our case) and the right one simulates the signal from the yellow wire from the main throttle channel. As you can see the right slider is disabled when mixing is off. Since the TREC can be for any 5 - 7 amp motor it isn't always used on the tail of a micro heli.
g) On the GUI, what is the !QUOT!Gain!QUOT!, what is it controlling?
Gain is the amount of mixing that will be applied to the throttle and tail signals. If I set this to 255 (max) the signal level created on the tail will match the signal level it see's on the throttle signal. If I set it to 127 the signal level created for the tail will be half the throttle signal levels it is reading. In that case max main throttle will give half tail motor power.
Marked23 - Dionysus themselves (Dan) has asked me to give some feedback on the testing I am doing with their TREC's mixing and a heading hold gyro. If I can get this happening then expect those FAQ's to be updated.
Happy tinkering guys!
Ended up putting a straightened paper clip with the end looped over through the center of the training skids link and then wedging the paper clip in between the two halves of the dining table so the heli wouldn't take off. Also moved the ping pong balls right up close to the skids so they could allow the heli to rotate easily.
Sat the laptop near it and hooked up the com cable to the TREC.
Spent an age trying to get the mixing to keep a steady tail through all the throttle levels. The duration it was taking me to get the throttle curve just right and the mixing gain right meant that the batteries kept draining down to the point that I would end up losing more and more power to the motor at set throttle positions. This in turn made it very tricky to get the curve right as I kept on over compensating as the power dropped.
Starting to think that I need an external power source (8.2V) to hook into the heli rather than constantly draining the batteries.
In the end I gave up and stuck with what I had ended up with on the throttle curve.
Gave that a quick fly without the GY240 AVCS HH mode on and the gain about 50%. Seemed quite stable mid hover but rotated a bit on the climb.
Then I turned on HH and had it's gain set to about 60%.
All seemed fine in a low hover...until I gave it more stick and then it started to oscillate the tail back and forth about 5 deg as it was climbing. It actually started to change heading slightly even though I wasn't moving the yaw stick left and right.
At this point I got the separate TREC gain controller and hooked it up to see if moving the mix gain on the TREC up and down by single increments made any difference. Well, it fixed the wag as I was climbing but I ended up throwing out the stability as I lowered the throttle. Even played with the GY240 gain levels to see if that could help.
At this point I realized that I need to put more of an effort into the throttle curve on the TREC...which I will get around to as soon as I can get a 25 amp power supply that has switchable voltage levels. Sick of draining the batteries.
In the meantime I figured that I may as well try switching off the mixer and play with the Advanced Options where I can feed the signal before the gyro into the TREC and it compares this with the gyro signal. It has acceleration / deceleration gain settings to help reduce the wag that you can get on HH gyro's.
That seemed reasonable in flight except for the constant small wag. Seemed to actually hold it's heading better than with the mixer on. Having the tail going when you haven't given it any throttle wasn't the best thing to be happening.
Then, out of interest, I grabbed my old PHA-01 all in one board and hooked up the GY240. Oh dear. The power for some reason was cycling off and on every second or so on both main and tail. Forget that idea.
So, at the end of a fun old day the mix-less setup yielded the better result all round. Given the wag-less condition of the tail at the low hover I suspect that if I can get the mix perfect in the first place across all throttle levels then I will have a far more stable HH.
Technical thought: on-board mixing is still floored as the throttle stick position will never always match the actual power / rpm produced in a consistent fashion due to the gradual drop in voltage from the battery. The main motor seems to be effected by this far more than the tail motor. As a result you end up with a mismatch even if you get the mix / throttle curve right at one voltage. That's the reason I feel a sensor to read the main rpm and use that as a reference for the mixer would be far more accurate. To tell the truth I think the best solution is to not have a separate electric motor for the tail in the first place.
Still, more setup and testing to be done to make things clearer on the subject. AND, the more people who give this a go the more accurate the conclusion.
Answers for Campbell Grant -
a) When the 3 to 4 pin adapter is connected between the main esc and the receiver, and the yellow auxiliary input wire is connected, does Mixing have to be enabled? And, if Mixing is disabled, must the yellow wire be disconnected.
ANSWER: Yes, the yellow wire is only used if you have the mixing enable OR if you are using the sampling option for the gyro signal (check latest 1.3 manual on this). Disconnecting it when mixing is disabled is not necessary.
b) In order to disable one of the BEC's, I have cut the middle servo lead on the TREC, i.e. I have only the two outer wires going to the gyro. Is this OK?.
ANSWER: That's fine but it may have been better to just slide the middle pin out of the connector and tape it up just in case you need it again in the future.
c) Am I correct in thinking that you do not need the mixing enabled? But, can it be beneficial to use mixing with a HH gyro.
ANSWER: I wish I could be definitive on the answer to this question but so far I haven't been able to get the mixing and throttle curve just right to tell you if it will be ok. At the points on the throttle curve with the mix is just right the heading hold has absolutely no wag so that in itself means that there is a good chance you could get it right. But at the end of the day if you dislike having to play with settings then a mix-less setup would be the go...provided you can get the gain on the HH gyro and the center position on the yaw channel just right in hover so that the tail doesn't wag. I had the TREC set to 72kHz but this didn't seem to make much difference to getting rid of the wag. More testing involved before I can be certain about all this.
d) In the instructions, under Advanced Gyro Settings, it details that you can use the 3 to 4 pin adapter between the gyro & the receiver, INSTEAD of between the main esc and the receiver. When is it advisable to use adapter between the gyro and the RX? Can I do this with my setup?
ANSWER: worth a try using this option when you are not using mixing. I gave it a quick go but haven't really had time yet to try different values. This option may very well be a good option to reduce tail wag. Let me know what results you have with this.
e) I.E. Is MIXING used when you do NOT have a HH gyro and ADVANCED GYRO CONTROLS used when you do have a HH gyro?
ANSWER: That's the general opinion going around at the moment but my objective is to see if a well set up on-board mixer will add benefit to a heading hold gyro.
f) I am also confused about the meaning of the “Main Throttle†in the “Controlling TREC from the computerâ€Â. I understand that the Mix Input is used to simulate the signal coming FROM the main motor, but I do not understand what is meant by: “The Main Throttle slider is the just like the prominent input to the ESC.“ Please can you clarify?
ANSWER: From what I can tell the left slider simulates the tail channel signal level (in our case) and the right one simulates the signal from the yellow wire from the main throttle channel. As you can see the right slider is disabled when mixing is off. Since the TREC can be for any 5 - 7 amp motor it isn't always used on the tail of a micro heli.
g) On the GUI, what is the !QUOT!Gain!QUOT!, what is it controlling?
Gain is the amount of mixing that will be applied to the throttle and tail signals. If I set this to 255 (max) the signal level created on the tail will match the signal level it see's on the throttle signal. If I set it to 127 the signal level created for the tail will be half the throttle signal levels it is reading. In that case max main throttle will give half tail motor power.
Marked23 - Dionysus themselves (Dan) has asked me to give some feedback on the testing I am doing with their TREC's mixing and a heading hold gyro. If I can get this happening then expect those FAQ's to be updated.
Happy tinkering guys!
08-15-2004, 01:16 AM
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RE: Is there a stand-alone main/tail mixer board on the market?
Here are the pictures of the setup I had for the heli on the dining table.
08-16-2004, 12:32 AM
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RE: Is there a stand-alone main/tail mixer board on the market?
dang those switchmode power supplies are expensive.
3-15V DC 25AMP max ...$299AU.
Anyone have a cheaper idea? Something that inputs from a car battery and can produce a variable output voltage at up to 15 amps might be cheaper....if I could find one.
3-15V DC 25AMP max ...$299AU.
Anyone have a cheaper idea? Something that inputs from a car battery and can produce a variable output voltage at up to 15 amps might be cheaper....if I could find one.
08-17-2004, 12:19 AM
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RE: Is there a stand-alone main/tail mixer board on the market?
Have to start from scratch with getting the mix right on the TREC anyhow as the new Razor MH V2 and Pheonix25 have turned up today from the US. The power delivered from this motor will not be the same at the same throttle positions I had with the default motor.
Also I need to ensure the that the mix gain on the TREC still leaves enough gap for extra input from the gyro or Tx rudder channel even when the throttle is 100%.
100% Throttle level --> mixer @ 75% --> TREC power level 75%. This should in theory leave 25% extra power if I apply extra via the rudder channel or if the GY240 needs to appy up to 25% extra if the tail starts to wonder right. I think this is half the reason I was having issues with the GY240 when I had the throttle channel up above 80% stick position.
Also I need to ensure the that the mix gain on the TREC still leaves enough gap for extra input from the gyro or Tx rudder channel even when the throttle is 100%.
100% Throttle level --> mixer @ 75% --> TREC power level 75%. This should in theory leave 25% extra power if I apply extra via the rudder channel or if the GY240 needs to appy up to 25% extra if the tail starts to wonder right. I think this is half the reason I was having issues with the GY240 when I had the throttle channel up above 80% stick position.
08-17-2004, 06:51 PM
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RE: Is there a stand-alone main/tail mixer board on the market?
Ouch! That Razor motor has some serious kick in it. Much faster RPM available. Dangerously fast. Might have to trim the trailing edge of the blades so I can run at a faster RPM. Can't get over how a motor that is half the size as the original brushed one can have so much power. Seriously expensive magnets or something? Might explain the price.
