[kreutz]

Modified UHU board for High Power Servo Motors

Some photos of the test setup and boards.

[contactirfu]

Modified UHU board for High Power Servo Motors

Some photos of the test setup and boards.

and I thought only my work bench looked messy! LOL

meanwhile would it be possible to add on small jumper type connectors like those on motherboards for external LED's

and what is it mounted vertically on the general PCB.

and once again Great Job Kreutz.

also I remember you posting some where on the unipolar thread about fixing of the Mosfet to the heat sink, can u tell how once again or point out to the right thread.

My best to U

Regards
Irfan

[rokag3]

and what is it mounted vertically on the general PCB.

Ir 21844 obviously

[rokag3]

sorry obviously not

[contactirfu]

think its the differential decoder

[Xerxes]

Congratulations Kreutz! I know the feeling

BTW, where did you find the black screw terminals? I tried to find similar ones but I couldn't find them.

[kreutz]

and what is it mounted vertically on the general PCB.

It is a modification I did to my original current limiting circuit, it has two modes, fast limit at 2.2 times the maximum continuous stall current , and Slow limit at the continuous stall current limit (adjusted by a potentiometer).

The system works as follow: When the current is below the slow current limit the PWM pulse width is the one set up by the speed control algorithm on the UHU chip, as soon as the slow limit is exceeded for about 3 seconds, the pulse width is limited in order to limit the maximum current, if the current peak reaches 2.2 times the continuous limit, then it will limit the current immediately. This way, the intermittent torque capacity (up to twice the nominal continuous torque) of the motor is better used while limiting the amount of time working in that region. Most motors have a peak stall current several times higher than the continuous stall current, so there is no danger to the motor.

I can add a second potentiometer if required (for Fast limit adjustment), but think that this way is simpler, cheaper and effective.

Regards,

Kreutz.

[kreutz]

Congratulations Kreutz! I know the feeling

BTW, where did you find the black screw terminals? I tried to find similar ones but I couldn't find them.

Hello;

They are from "Newark in One", part number: 14F2034 rated at 25 Amp /300 Vdc

Thank you and Regards,

Kreutz.

[kreutz]

and I thought only my work bench looked messy! LOL

meanwhile would it be possible to add on small jumper type connectors like those on motherboards for external LED's

and what is it mounted vertically on the general PCB.

and once again Great Job Kreutz.

also I remember you posting some where on the unipolar thread about fixing of the Mosfet to the heat sink, can u tell how once again or point out to the right thread.

My best to U

Regards
Irfan

The photos were taken after cleaning up the bench!!

You can solder a couple of wires to the LED pads and extend them outside the board, note that the LEDs are on the same circuit as the motor power supply so there will be necessary to leave some clearance to the Ground connected metallic parts of your enclosure.

Mounting the Mosfets to the heat-sink is easy, you bend the leads up 90 degrees from the Mosfet tab, and they will get perfectly aligned to the holes on the PCB. I will post a photo when I disassemble this board. The improvised heat-sink is a 1/8" Aluminum plate, same external dimension as the board. I suggest using 1/4" Aluminum plate or thicker, that way you can thread the mounting holes and save a few #4-40 nuts. TO-247 Thermal pads (and possibly thermal grease depending on the pads used) are required for mounting all the Mosfets and the 7805 regulator.

Remember that I did not test at maximum current due to the lack of a proper load for the motors, The board might require additional heat-sinking at high loads, so, please, use a plate with a machined surface on both sides in order to make it easier later. As it is now, without load on the motors, it did not even get warm working at 185 volts.

By the way, the filter circuit (The original cause of all of this Fuzz) does not get hot either.

Regards,

kreutz.

[kreutz]

Modified UHU board, more detail.

This is the prototype board used for the tests, the final PCB will look approximately like this one but will have some new modifications, different low power I/O connectors, opto-isolated EMG-Stop input and Output signals, and different (isolated) RS-232 interface..

[kreutz]

I want to hear some opinions...

Question: Do you prefer to have the Emergency_Stop input and Output (Fault signal) opto-isolated on the board, or rather isolate them on the external B.O.B.?

If you prefer to have them on-board it will increase a little the cost of the boards because of the optocouplers, some resistors, and connectors (need more terminal positions for external +5V and Ground inputs), and of course, will complicate just a little more the final PCB layout.

Remember, you either isolate them on board or isolate them on the B.O.B. (You can also leave them unconnected)
DO NOT USE THEM WITHOUT ISOLATION, We will be working with Lethal Voltage and Current Levels.

Thank you,

Kreutz.

[contactirfu]

I want to hear some opinions...

Question: Do you prefer to have the Emergency_Stop input and Output (Fault signal) opto-isolated on the board, or rather isolate them on the external B.O.B.?

If you prefer to have them on-board it will increase a little the cost of the boards because of the optocouplers, some resistors, and connectors (need more terminal positions for external +5V and Ground inputs), and of course, will complicate just a little more the final PCB layout.

Remember, you either isolate them on board or isolate them on the B.O.B. (You can also leave them unconnected)
DO NOT USE THEM WITHOUT ISOLATION, We will be working with Lethal Voltage and Current Levels.

Thank you,

Kreutz.

Unless you are offering a BOB with optos for the e-stop

would prefer to have opto on the boards, lot of people will surely venture into this and u sure dont want them to risk injury! just make sure the optos are universally (commonly used ) optos.

Thanks once again kreutz.

RGDS
Irfan

[kreutz]

Unless you are offering a BOB with optos for the e-stop ......

Irfan

No, I won't offer any B.O.B.s, I have too many projects to develop and a B.O.B. is not included. I also need some free time

Regards,

Kreutz.

[contactirfu]

No, I won't offer any B.O.B.s, I have too many projects to develop and a B.O.B. is not included. I also need some free time

Regards,

Kreutz.

U answered your own Q Kreutz.

lets have a completely protected board, may be it adds a dollar or more but no comparison to a human life right!

RGDS
Irfan

[kreutz]

U answered your own Q Kreutz.

lets have a completely protected board, may be it adds a dollar or more but no comparison to a human life right!

RGDS
Irfan

Thanks, I was referring to a generic external B.O.B. board needed for LPT (parallel) port interface.

I included a B.O.B. functionality on another project (Bipolar Micro-stepper 4 axes set) but, in that case, it made sense to offer a complete package. I also took the necessary steps to make sure my interface board would not compete unnecessarily with some business offering B.O.B. boards, by including the translators on them, so, making it an specialized board only suitable for my projects.

In this case, I don't feel bad modifying the UHU board to extend its functionality, the original board was already public domain, and being a DIY board it really does not compete with established businesses. In any case, it will produce a healthy push on those businesses, will put some pressure (on them) to keep improving their products, and that, in fact, will benefit everyone in this field.

Regards,

Kreutz.

[contactirfu]

/?

[MrWild]

Whatever gets the job done without adding to your time burden. I think anyone with the desire to run higher end servos is going to have a higher end BOB. Mine is a Campbells design. I also have a CNC4PC opto isolated for a stepper controlled router. A non opto BOB just seems foolish with so many good ones available and opto chips so cheap for DIYs.

[MrWild]

Kreutz,

In keeping withthe nature of this "Beer ware," is it possible to send you some beer or wine? There are alot of micro breweries in my area and I'd like to show gratitude in some way.

[kreutz]

Modified UHU for High Power Servo Motors, Final Assembly Drawings Rev1.0

I decided to go ahead and add the optoisolated E-Stop feature. It also has the possibility of using an external +5 volt power supply isolated from the PC and the Motor ground, if you don't want it just solder a couple of traces together in order to use the PC +5 Volts and Ground (from the USB port) by means of a USB connector on board. That USB cable will power the isolated RS-232 interface when Tuning the servo.

If you are not supplying the E-Stop circuit from the USB cable it can be disconnected after tuning the PID parameters.

E-Stop opto-couplers are TLP127 (qty=2), the RF isolated interface uses an ADUM1201ARZ-RL7, Those are SMD, but big enough to be soldered with a normal soldering iron (with a fine tip).

Step and Direction signals use the same opto-coupler used on the original UHU board. I had to use SMD components in order to keep the board dimensions at 5" x 6". Added two 3 position 5 mm pitch connectors for the low voltage interface. Another 5mm pitch connector (2 positions) is used for the +15 volts power supply input. (you can use those 5mm pitch connectors that can be attached together and in that case you need 4 two position connectors (3 together).

[kreutz]

Kreutz,

In keeping withthe nature of this "Beer ware," is it possible to send you some beer or wine? There are alot of micro breweries in my area and I'd like to show gratitude in some way.

Thank you, MrWild. It would be nice.

Regards,

Kreutz.