Build a 5/6ch pistol Tx for $120

[meao]

Windscreen wipers

[edwalsh18]

or in america we say windshield wipers.

nice work clockworks! i got mine a few days ago and...

you remember how the guy couldn't get it to work? you know the guy that sold it to me? well i installed the driver, plugged it in and nothing...:-(
so i searched the internet for hours, i found a website with a video on how to set it up... nothing!!! well then i went back to the million page thread in the other forum and read it from page 1 after a few hours i found a link to a site that had a driver for vista users, i am running windows 7 not vista. i installed the driver and VIOLA!!! SHE WORKS!!! works great i got all the channels to work, messed with the software a little then bench tested it with my servos and esc, they all work. esc is acting a little retarded but i am sure it is no big deal, just have to mess with the settings a little, or swap it to the pistol first.

but hey, you know that the whole "don't install the software before the drivers" is not true. i installed the software on my laptop a month ago and it still worked fine. i guess i got lucky! it was real cheap and i didn't even have to wait 20 days for it to ship. i will try to bind it with my other rx to see if that works. now i just have to look for a cheap if not free-ish pistol tx for the swap

[meao]

Originally Posted by edwalsh18

or in america we say windshield wipers.

Thanx Edwalsh

Originally Posted by edwalsh18

now i just have to look for a cheap if not free-ish pistol tx for the swap

Steve and me use that ones: http://cgi.ebay.es/HSP-PISTOL-GRIP-2...3286.m63.l1177

Waiting for your build.......

[Galladon]

Great thread guys!
I'm currently trying to stuff a gutted HK 4ch 2.4Ghz in an old JR Tx. Just like on your radio, the throttle and steering trim works by mechanically changing the original stance of the pot.
However, this is not possible on the JR. So I need to add some external trim pots. How should I wire these up? Parallel on the 3 wires from the steering pot?
And what value pots should I look at? The steering and throttle pots are around 5K, centering at 2.6K.


Secondly, the wire for the coaxial antenna came off. On the board there's a square marked 'Jack1', but it consists of four contact points. Any difference between them, or should I just pick the outermost?


Thanks for the help!

[clockworks]

Originally Posted by edwalsh18

or in america we say windshield wipers.

nice work clockworks! i got mine a few days ago and...

you remember how the guy couldn't get it to work? you know the guy that sold it to me? well i installed the driver, plugged it in and nothing...:-(
so i searched the internet for hours, i found a website with a video on how to set it up... nothing!!! well then i went back to the million page thread in the other forum and read it from page 1 after a few hours i found a link to a site that had a driver for vista users, i am running windows 7 not vista. i installed the driver and VIOLA!!! SHE WORKS!!! works great i got all the channels to work, messed with the software a little then bench tested it with my servos and esc, they all work. esc is acting a little retarded but i am sure it is no big deal, just have to mess with the settings a little, or swap it to the pistol first.

but hey, you know that the whole "don't install the software before the drivers" is not true. i installed the software on my laptop a month ago and it still worked fine. i guess i got lucky! it was real cheap and i didn't even have to wait 20 days for it to ship. i will try to bind it with my other rx to see if that works. now i just have to look for a cheap if not free-ish pistol tx for the swap

I remember that you got a deal because the seller had problems.
Glad you got the software working. I think I messed my desktop PC up by connecting the interface cable before I loaded the drivers. It works fine on my laptop.

Have you re-calibrated the ESC to the new radio?

The Tx that Carlos linked to is worth paying $20 for. It's a perfect fit.

[clockworks]

Originally Posted by Galladon

Great thread guys!
I'm currently trying to stuff a gutted HK 4ch 2.4Ghz in an old JR Tx. Just like on your radio, the throttle and steering trim works by mechanically changing the original stance of the pot.
However, this is not possible on the JR. So I need to add some external trim pots. How should I wire these up? Parallel on the 3 wires from the steering pot?
And what value pots should I look at? The steering and throttle pots are around 5K, centering at 2.6K.


Secondly, the wire for the coaxial antenna came off. On the board there's a square marked 'Jack1', but it consists of four contact points. Any difference between them, or should I just pick the outermost?


Thanks for the help!

On my last build, I wired a 2K trim pot to each side of the main pot's track, between the pot and positive and between the pot and negative. This works, but it also changes the end point.
I think that wiring another pot in parallel will work better as a trim, but I haven't tried it yet. It's on my list of things to do, hopefully I'll get time to try it tomorrow.

That RF PCB looks the same as mine. The centre conductor of the antenna wire goes to the contact point on the right (3 o'clock position). The other 3 points are ground. The shield can go to any of them. Mine goes to the 12 o'clock and 9 o'clock positions.

Good luck soldering the wire back on - I needed to use a 5x binocular magnifier just to see it clearly!

[meao]

Driver 1:(xp/7)
PL-2303 USB to Serial Bridge (H, HX, X) Installshield Driver Setup Program
Installer & Build date: 1.0.5.18 (20090723)
Windows 98/ME Driver: v2.0.0.19
Windows 2000/XP/Server2003 (32 & 64-bit) WDM Driver: v2.0.9.122
Windows Vista/7/Server2008 (32 & 64-bit) WDF Driver: v3.3.5.122
NOTE: For Windows 7, please use RC build 7100 or above.
http://www.prolific.com.tw/support/f...ler_v10518.zip



Driver 2:(Vista)
PL-2303 USB to Serial Bridge (H, HX, X) Installshield Driver Setup Program v2.0.0.19 for Win98SE/ME v2.0.2.1 for Win2K/XP/2003 (XP Logo Certified) For Prolific USB VID_067B&PID_2303 Only (for Mobile Phone, GPS, Modem, IrDA USB Serial Cable)
http://lib.store.yahoo.net/lib/coold...l-adapters.zip

[meao]

Originally Posted by clockworks

On my last build, I wired a 2K trim pot to each side of the main pot's track, between the pot and positive and between the pot and negative. This works, but it also changes the end point.
I think that wiring another pot in parallel will work better as a trim, but I haven't tried it yet. It's on my list of things to do, hopefully I'll get time to try it tomorrow.

In parrallel gives the same result, "less" end point.

I havent tested it yet, but it could work adding a pot from the middle contanct of the pot to the input on PCB.

[clockworks]

Playing the steering rotary switch yesterday, I noticed that the servo travel was quite limited. Had the same thing with my DX6i conversion, but not quite as bad.

Problem is the limited rotation of the pot. The original stick pot goes down to about 800 ohms at each end. The wheel pot only drops to about 1500 ohms.
This gives around half the steering travel that the original Tx had.

Solution is to allow the pot to move more. There are 2 things limiting rotation - the sprung lever on the steeringwheel spindle catches the case, and the wheel has a limiting stop.

I cut away part of the standoff that supports the pot assembly:


I also shaved a couple of millimetres off the lever:



Without the wheel fitted, the pot now moves enough to push the cam/lever "over centre".

I carefully trimmed away part of the limiting projection on the case that prevents the wheel turning full circle:


The pot now drops to around 1K, so I get around 90% of the original steering servo movement. It can be "overdriven" to 120%, so that should be enough

[mrklaw]

I'm a bit confused about using pots for winch, lights, dig etc. Isn't that exactly what people are using 2 and 3-pos switches for? the switches basically replicate servo travel on the rx end which is what most winches want, or digs, or gear shifters?

[clockworks]

Originally Posted by mrklaw

I'm a bit confused about using pots for winch, lights, dig etc. Isn't that exactly what people are using 2 and 3-pos switches for? the switches basically replicate servo travel on the rx end which is what most winches want, or digs, or gear shifters?

I'm confused by this as well. Switches seem to be much more useful for the auxiliary channels. I suppose it's possible that there may be some electronic control units that need a proportional, rather than switched, signal.
No harm in having a pot and a switch on the same channel - gives you the option to use whichever control method you need - as long as the pot doesn't get moved when you are using the switch. That would mess up the end points.

I'm going to fit both on ch5. I don't have a use for ch5 yet.

[clockworks]

Time to start the wiring. I've decided on the switch layout:


Wires and resistors added to the ch5 3-position switch and pot:


Wires added to the rotary steering switch:


And the wires running down to the trimpot PCB:


Wiring for the 2-position switches:


The power PCB fitted:


Connecting the main PCB wiring:

Because I'm fitting trims and EPA pots in the base, all the channels except ch2 (throttle) have wires running from the pots/switches down into the battery compartment. They will pick up the 5v and ground connections from the trims, so the red and black wires from the main PCB aren't used. I tied them back with a piece of heatshrink.

PCB wiring completed:


All that's left to do is make and fit the trimpot PCB in the battery bay, then I'll post the schematics.

[meao]

Hi Steve, great work!

But I don't understand why are you adding this 2 resistors:



I mean, if you have the pot parallel to the switch, you don't need the resistors, isn't it?. Or you are looking for a "reduced travel"?.

Cheers, Carlos.

[clockworks]

Yes, the resistors are there just to reduce the travel.
I noticed that ch5, when controlled by the VR pot, went "off the scale" in the setup software. This might over drive the servo, so I fitted the resistors to limit the travel slightly when the switch is used.

[meao]

Ok

Tomorrow I'll give you the links of the TX's pictures. What do you need, just a "general view" or need also an "inside view"?.

[benzy2]

Looks like a great budget radio project. Too bad its a bit out of my electrical abilities.

[clockworks]

Originally Posted by meao

Ok

Tomorrow I'll give you the links of the TX's pictures. What do you need, just a "general view" or need also an "inside view"?.

Hi Carlos

I just need a general view so that people know what to buy on eBay.

[clockworks]

Originally Posted by benzy2

Looks like a great budget radio project. Too bad its a bit out of my electrical abilities.

There's nothing really difficult here. If you've got a decent soldering iron, good eyesight and steady hands, you can do it.
The wiring looks complicated, but it isn't - there's just a lot of it! I'll post the schematics soon, once it's built and fully tested.

[clockworks]

I connected the radio to my crawler for the first time today. All the controls work as expected, but I get jitter on all the servos. Not a huge amount, but enough to be annoying.
It also shows up on the PC software - the bars on the graphical display jump around very slightly. I don't remember seeing this when I started the build.

I'll need to look into this. May be a bad Tx, or it might be related to the 4-cell mod (removing the voltage regulators means that the RF module is no longer isolated from the rest of the Tx - might be modulating the 5v rail).

I don't think that it's a design or wiring problem, as my DX6i-based Tx doesn't have any problems.

Have you noticed any problems like this, Carlos?

[Racer4Life]

Great write-up. This is awesome.

I could never pull this off without burning myself, or loosing my temper and throwing it accross the room.