Electrical Engineering V3

[Ddrl46]

[QUOTE=pentium;48608172]So it was the tant?
Next time you come across one of these awesome and cheap plugins tell me so I can fill the hole in generator with something.[/QUOTE]

Yes, it was that axial tantalum capacitor:
[thumb]http://i.imgur.com/DbmsM7d.jpg[/thumb]

Luckily it didn't do that much damage besides two traces and the solder mask:
[thumb]http://i.imgur.com/I06VbtD.jpg[/thumb]

Wouldn't say it was cheap however, still paid about half the going rate for these plugins and got to pay the import fees.

Also this type of plugin wouldn't work in that sweeper mainframe of yours, you need the older style plugin (HP 86290B for example).

[Papkee]

So I need help with another thing radio related, this one is because I'm not the best when it comes to reading schematics.

Here's what I'm looking to build.

[t]http://batlabs.com/images/rib_mod.jpg[/t]

It's an interface to go between a serial connection from a computer and an alleged "proprietary protocol" used to program older motorola radios.

Now, it looks to me that all the complex circuitry is only there to do level conversion. It looks like it's stepping the ~10V from the PC connection to 5v, and vice-versa.

I don't know, however, what the OpAmp is doing there, or why TX and RX and connected through it.

What I want to do is forgo the serial connection and use an FT232 to do serial communication to the radio. It seems like I should be able to directly connect TX and RX to the pins of the DB25 connector, but again I don't know why the OpAmp is there or if there are other things going on that are needed.

There's little to no documentation about Moto's protocol for programming these things, so this is the best I have to go off of.

[Goz3rr]

Decided to do embedded systems etc instead of software engineering in school since I already know the latter. Going to take an atmega32 home for the weekend and mess around with that, certainly is going to be interesting since all my life i've done high level stuff

All the boards were made by a teaching assistant because (teacher's words) "in 2011 they didn't realize they could get this stuff on ebay for next to nothing)"

[t]http://i.imgur.com/5hH0jDG.png[/t]
[t]http://i.imgur.com/LLGYsKa.png[/t]
[t]http://i.imgur.com/uDctbTb.png[/t]

[Chryseus]

[QUOTE=papkee;48611380]So I need help with another thing radio related, this one is because I'm not the best when it comes to reading schematics.[/QUOTE]

It looks like a differential 5V bus.
When TX is high Bus+ is pulled to ground and Bus- is at some positive voltage clamped by the output zener diode.
When TX is low Bus+ is 5V and Bus- is left floating (probably at 0V).
For receiving I assume Bus+ is pulled down.

The op-amp simply is comparing which bus is higher, if Bus+ is higher than Bus- it outputs low, if Bus+ is lower than Bus- it outputs high.
The signal is then inverted by Q7 and Q6 level shifts it between 5V and -5V.

More or less the same is done with the busy signals.
When DTR is high /busy is at some positive voltage, this turns on Q5 which grounds busy, RI and CTS is then at 5V.
When DTR is low /busy is floating (at 0V I assume) and busy is at 5V with -5V out at RI and CTS.

Power supply is your standard 5V regulator driving a switched capacitor 5V inverter.
These voltages are not even RS232 standard which could cause some PCs to receive garbage, you could certainly convert it for use with a good old UART to USB with minimal modifications.

[QUOTE=Goz3rr;48611759]All the boards were made by a teaching assistant because (teacher's words) "in 2011 they didn't realize they could get this stuff on ebay for next to nothing)"[/QUOTE]

They look nice though, probably easier to fix as well if something goes horribly wrong.

[Papkee]

[QUOTE=Chryseus;48613312]you could certainly convert it for use with a good old UART to USB with minimal modifications.[/QUOTE]

If I don't need the higher voltages on the serial side, would all I need to do be just create a circuit for the differential logic? If so, don't tell me the specifics because I want to see if I can design it myself.

Thanks again for that analysis.

[editline]4th September 2015[/editline]

And are those negative voltages required? Basically I'm just looking to make a simple logic circuit with inverters.

[Chryseus]

[QUOTE=papkee;48613357]And are those negative voltages required? Basically I'm just looking to make a simple logic circuit with inverters.[/QUOTE]

Negative voltage are only needed with RS-232 so no.

[Papkee]

[QUOTE=Chryseus;48613382]Negative voltage are only needed with RS-232 so no.[/QUOTE]

Great, thanks. That makes this so much easier and cheaper to build.

[Fourier]

[url]http://www.ebay.de/itm/DC-IN-5-30V-OUT-1-25-26V-2a-constant-voltage-current-buck-converter-LED-Driver-/231526132957?hash=item35e8086cdd[/url]

Look at this gem I found (for a friend)!

[nikomo]

LED drivers are dime a dozen, quite common gear.
Looks like a nice package though.

[Ddrl46]

So I was getting intermittent errors on my HP 8350A sweeper mainframe that indicated that one of the supply rails was being shorted. Took the plugin out of my mainframe and the error would go away, so I started probing around and noticed that the -10V power supply was being shorted somewhere. Some probing later I found out that it was being shorted by the power amplifier, which got me worried that the power amplifier was in some way broken.

Turn out the problem was a bit simpler, can anyone guess?
[thumb]http://i.imgur.com/4vptyJY.jpg[/thumb]

After removing the nut:
[thumb]http://i.imgur.com/FWQLFqf.jpg[/thumb]

Ah well, at least I got to dig a bit deeper into the fancy RF components of this plugin:
[thumb]http://i.imgur.com/GKVYXoN.jpg[/thumb]

[thumb]http://i.imgur.com/JSAaPwJ.jpg[/thumb]

[No_Excuses]

Hey people here like HP test gear. I just ordered a broken 6034A programmable powersupply off ebay. 60V/10A/200W. I currently have no bench supply unless you count a 12V atx PSU as one...it's somewhat miraculous I've been able to do what I do without one. Nothing like slapping together a simple regulated power supply whenever I need a voltage that isn't 12V.

[thumb]http://www.woutersenwouters.be/sites/default/files/styles/product_detail/public/product_pictures/HP%206034A%20f.jpg?itok=NwjGin-6[/thumb]

--------------------------------------------

And unrelated to the first part of my post:

This switchmode powersupply I have has failed in a weird way. It outputs 30V instead of it's specified 24V +-5% yet still delivers its rated current. At least I assume it has failed because the device its meant to power gets angry with it, yet said device runs fine off a different 24V supply.

Interestingly it also doesn't trip the over voltage protection. I analyzed the OVP circuit and found it's meant to trip at about 38V. I temporarily changed it to trip at 28V and it tripped on startup, so that was kind of curious.

I have spent way too much time on this thing at this point. I'm questioning if it actually failed or if it came out of the factory like this. I tried modifying the feedback circuit and I had the output voltage reading 24V but the voltage becomes very unstable. I did this by modifying the 53.6K ohm resistor in my crude drawing so it was around 45k.

[url=http://imgur.com/aoIG8Dx][img]http://i.imgur.com/aoIG8Dxm.jpg[/img][/url]

Pin 3 is the "FBCTRL" or Flyback control pin. "Under normal operating conditions, the converter regulates the output voltage. The voltage on the FBCTRL pin then varies between 1.4 V for the minimum output power and 2 V for the maximum output power."

[img]http://i.imgur.com/133awopl.png[/img]

[img]http://i.imgur.com/2Us4CSXl.png[/img]

[URL="http://www.nxp.com/documents/data_sheet/TEA1751LT.pdf"]Datasheet for the TEA1751 SWMPS Control IC[/URL]

[Ddrl46]

[QUOTE=No_Excuses;48622088]Hey people here like HP test gear. I just ordered a broken 6034A programmable powersupply off ebay. 60V/10A/200W. I currently have no bench supply unless you count a 12V atx PSU as one...it's somewhat miraculous I've been able to do what I do without one. Nothing like slapping together a simple regulated power supply whenever I need a voltage that isn't 12V.

[thumb]http://www.woutersenwouters.be/sites/default/files/styles/product_detail/public/product_pictures/HP%206034A%20f.jpg?itok=NwjGin-6[/thumb]

----

This switchmode powersupply I have has failed in a weird way. It outputs 30V instead of it's specified 24V +-5% yet still delivers its rated current. At least I assume it has failed because the device its meant to power gets angry with it, yet said device runs fine off a different 24V supply.

Interestingly it also doesn't trip the over voltage protection. I analyzed the OVP circuit and found it's meant to trip at about 38V. I temporarily changed it to trip at 28V and it tripped on startup, so that was kind of curious.

I have spent way too much time on this thing at this point. I'm questioning if it actually failed or if it came out of the factory like this. I tried modifying the feedback circuit and I had it reading 24V then the output becomes very unstable. I did this by modifying the 53.6K ohm resistor in my crude drawing so it was around 45k.

[url=http://imgur.com/aoIG8Dx][img]http://i.imgur.com/aoIG8Dxm.jpg[/img][/url]

Pin 3 is the "FBCTRL" or Flyback control pin. "Under normal operating conditions, the converter regulates the output voltage. The voltage on the FBCTRL pin then varies between 1.4 V for the minimum output power and 2 V for the maximum output power."

[img]http://i.imgur.com/133awopl.png[/img]

[img]http://i.imgur.com/2Us4CSXl.png[/img]

[URL="http://www.nxp.com/documents/data_sheet/TEA1751LT.pdf"]Datasheet for the TEA1751 SWMPS Control IC[/URL][/QUOTE]

Did you strap the sense inputs of that supply to the output or switched it to local sense mode? Most big supplies like that get mad if you don't.

[No_Excuses]

[QUOTE=ddrl46;48622127]Did you strap the sense inputs of that supply to the output or switched it to local sense mode? Most big supplies like that get mad if you don't.[/QUOTE]

Sorry the SWMPS is just a small stand-alone brick unit, not the HP one pictured.

[Ddrl46]

[QUOTE=No_Excuses;48622218]Sorry the SWMPS is just a small stand-alone brick unit, not the HP one pictured.[/QUOTE]

Oh, nevermind then.

[No_Excuses]

I'm gonna take out the optocoupler and stick a variable resistor in the transistor side. Also [URL="http://www.ebay.ca/itm/251425842791?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT"]these ebay resistor packs are really sweet[/URL].

It's come in handy so far. China puts out a lot of shit products but I gotta give them props for helping out my hobby so much.

[AuntJimmy]

Yeah ebay's resistor kits can be pretty nice

[img]https://i.imgur.com/yyFFyJh.png[/img]

[gamerpaddy]

[QUOTE=halofreak472;48623677]Yeah ebay's resistor kits can be pretty nice

[img]https://i.imgur.com/8gPlpkH.png[/img][/QUOTE]
recently bought the same for zener diodes. 33 types 10pcs each, for like less than 5$. they even wrote the Voltage on the packaging. 10/10 would buy again.
[url]http://www.ebay.com/itm/161657716543[/url]

[TCWilliamson]

[media]http://www.youtube.com/watch?v=QCsiBLz6qqo[/media]

After seeing this I realized I really need to get around to doing a robotics project and make something just as awesome...

But I don't know what. Does anyone have any cool suggestions of a robot in a game that hasn't been made yet?

Half tempted to just make my own one of those, but then you are forever labeled a copy-cat.

[Fourier]

Well make 3D model first, with all the servos (you can download 3D model) and electronics.

[Nightrazr]

[img_thumb]http://i.imgur.com/uS4iXez.jpg[/img_thumb]

Oh god what have I started.
Chinese board and shitty soldering skills are the cause of this disaster area. :v:

[TCWilliamson]

[QUOTE=Fourier;48626802]Well make 3D model first, with all the servos (you can download 3D model) and electronics.[/QUOTE]

That's how I intended to do it in the first place, maybe I will make my own GLaDOS style robot, but different. Combine version?

[Fourier]

Make a turrent from Team Fortress 2?

[TCWilliamson]

[QUOTE=Fourier;48627058]Make a turrent from Team Fortress 2?[/QUOTE]

Been done: [media]http://www.youtube.com/watch?v=Uy1Ryxe44m0[/media]

:C

Why is originality so hard?

[Fourier]

Well they haven't been original in the first place, they copied model from team fotress 2...

[TCWilliamson]

[QUOTE=Fourier;48627191]Well they haven't been original in the first place, they copied model from team fotress 2...[/QUOTE]

That is true, however I was actually more referring to the originality of bringing x from a game into the physical world.

[LoneWolf_Recon]

[URL="https://blurppy.files.wordpress.com/2012/09/mg_rex_4997.jpg"]Metal Gear Rex[/URL] with some servos and a Biped Balancing algorithm?

Or to make things easy, why not just the [URL="http://img09.deviantart.net/ae50/i/2013/101/3/9/the_shagohod_tank__aka_treading_behemoth__by_annihilator79-d61dko0.jpg"]Shagohod[/URL]?

[Nightrazr]

Rex, definitely.

[TCWilliamson]

Shagohod seems pretty cool but whoever designed the rex needs a punch in the face.

[img]http://i.imgur.com/cEiixQY.png[/img]
that is an enemy's wet dream.

A Mech would be cool to look into making in the future once I have got more experience with coordinated motion (I should have more then I currently do given my current job is Motion Control, haha.)

I have been thinking about tanks, the main issue there is decent tracks are quite hard to deal with, maybe later on as a more advanced project.

I'm gonna go have a mess around with CAD and a pile of A4 paper and a pencil and see what I can come up with.

[pentium]

So I cleaned my bench off to try and fix that Nicolat scope I got two or so months ago.
Wouldn't fit on the bench so I put it on the floor and brought it up on a variac because the linear power supply reminded me of a small nuclear device. It woke up fine and the controls seem to respond and vary brightness intensity of the screen but there's no electrostatic horizontal or vertical deflection. :(

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/CGS_1050.jpg[/IMG]

Before I try and figure out why both are dead I'll try and repair the other third of the power supply that seemingly powers the digital side. It looks like whoever the hell used it last kept clipping out capacitors as they shorted and blew up and then eventually something hit the PSU and it must of stopped working completely...or the ripple finally did the regulators in. Too early to tell.

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/CGS_1052.jpg[/IMG]
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/CGS_1053.jpg[/IMG]

[fpro]

What has changed in LEDs over the last 5 years that made them valuable in growing veggies/plants? I want to buy several dozen 5 watt LEDs of various wavelengths off ebay to use as a light source. But I got to thinking, what is difference between these and the 5w LEDs of yesteryear?

Also, if I run an LED on a DC current, what will the flicker rate normally be? I want to experiment and see if flicker rate will have any effect on a plants growth.