Electrical Engineering V3

[No_Excuses]

Yeah $100 should get you something fairly decent. Lots of Chinese ones on ebay that seem pretty capable. I'm more into buying older name brand gear because I'm poor and have a great appreciation for older electronics.

Also normally I'm here asking you patient people questions but this time I have something to show off. I spent some time doing an electrical refurbish of an old audio mixer for a customer.

[img]http://i.imgur.com/3B3RBj3l.jpg[/img]

[URL="http://imgur.com/a/sVnqq"]Full gallery and descriptions[/URL]

[No_Excuses]

Oh man I killed the thread. Here's something else I whipped up last night. NTC thermistor calculator where you can specify a temperature and voltage range and it spits out the appropriate resistor values to achieve your goals.

[URL="https://www.dropbox.com/s/qubs69671un1yyo/NTCcalc.rar?dl=0"]https://www.dropbox.com/s/qubs69671un1yyo/NTCcalc.rar?dl=0[/URL]

At first it seemed like nothing special but go ahead and take a look at the equations in cells B31 and G31. I had an equation three lines long when I decided to get wolfram alpha to isolate the variable for me since there was no way I could have done it.

[Chryseus]

[QUOTE=No_Excuses;48736663]Oh man I killed the thread. Here's something else I whipped up last night. NTC thermistor calculator where you can specify a temperature and voltage range and it spits out the appropriate resistor values to achieve your goals.

[URL="https://www.dropbox.com/s/qubs69671un1yyo/NTCcalc.rar?dl=0"]https://www.dropbox.com/s/qubs69671un1yyo/NTCcalc.rar?dl=0[/URL]

At first it seemed like nothing special but go ahead and take a look at the equations in cells B31 and G31. I had an equation three lines long when I decided to get wolfram alpha to isolate the variable for me since there was no way I could have done it.[/QUOTE]

Very nice!
Added to OP along with some other software.

[ithon]

so Dialog semi bought Atmel?
[url]http://www.dialog-semiconductor.com/content/dialog-semiconductor-acquire-atmel-46-billion[/url]

what?

[pentium]

So some might remember I was having a CMOS latchup issue on an RS-232 to 20ma current loop adapter I built. The adapter and a peripheral RS-232 device (a modem) would initialize at the same time but the brief instance where the two devices were not initialized and the data lines were unstable would throw the MAX232 on the adapter into latchup and burn it out.
The easiest solution was to power sequence the devices. Because the modem already used a 5v relay to control the 13v AC it needs I simply purchased one of those chinese delay relay modules, stripped off the terminal blocks and replaced the 12v rated relay for a 5v model. There was also an LED in series with with the 555's output and the transistor that turned the relay on or off. At 5v it did not allow enough juice to flow and the relay coil was only seeing about 2v so I removed it and bridged the pads so that the full output of the 555 ran through a resistor and then into the transistor. It was then mounted inside the old relay enclosure and a small hole drilled so I could adjust the pot without opening the box up.

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_1088.jpg[/IMG]
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_1089.jpg[/IMG]
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_1090.jpg[/IMG]

The result is that when the interface is turned on there is an impressive number of relays that click and after half a second the modem comes up and the adapter no longer latches up.

[No_Excuses]

I fucked up something fierce here.

Was heating this IC up with hot air to remove it and the conformal coating around the area bubbled up and pulled away like 20 components from the board. Gooodaaammit there goes like a $180 job. I was debating using the soldering iron...instead I put kapton tape around the surrounding area and went for it with the air. Won't do that again.

[url=http://imgur.com/vuMsAw6][img]http://i.imgur.com/vuMsAw6l.jpg[/img][/url]

Actually I think I'm calling this one a failure for now. Some of 0402 devices have teleported into another dimension known as my floor so unless I can find a schematic I've got no hope.

[paindoc]

Quick question, would cleaning the dust out of my hardware mixer and cleaning contacts reduce audible noise? My mixer generates a fuck load of noise through the headphones output, especially on my headphones since I think they're pretty low impedance.

[editline]23rd September 2015[/editline]

Also, what's the cheapest way to pick up comparators and other common ic's for hardware synths? I can scavenge for caps and resistors, pots are something I'll have to buy though. The more money I can save the better, however. Is surface mount a fair idea? I'll have access to a reflow oven and pcb etcher

[No_Excuses]

[QUOTE=paindoc;48743998]Quick question, would cleaning the dust out of my hardware mixer and cleaning contacts reduce audible noise? My mixer generates a fuck load of noise through the headphones output, especially on my headphones since I think they're pretty low impedance.

[editline]23rd September 2015[/editline]

Also, what's the cheapest way to pick up comparators and other common ic's for hardware synths? I can scavenge for caps and resistors, pots are something I'll have to buy though. The more money I can save the better, however. Is surface mount a fair idea? I'll have access to a reflow oven and pcb etcher[/QUOTE]

Pots shouldn't be a problem unless you hear the noise only when you're adjusting them. Whats the model of the mixer?

[rsk_]

Has anyone got any experience with I2C and more specifically Afro ESCs?

[DrLuke]

[QUOTE=Dorkslayz;48745401]Has anyone got any experience with I2C and more specifically Afro ESCs?[/QUOTE]

Just ask your question

[rsk_]

[QUOTE=DrDevil;48745991]Just ask your question[/QUOTE]

Sure.

I'm building a Quadcopter but i'm having a few issues with communicating with my [URL="http://www.hobbyking.com/hobbyking/store/__39708__Afro_ESC_30Amp_Multi_rotor_Motor_Speed_Controller_SimonK_Firmware_.html"]ESCs[/URL] via I2C. My Raspberry Pi is recognising my MPU6050 sensor just fine, but it's not recognising one of the ESCs and the other is showing up at a completely random address (0x29). I edited and flashed the firmware for both of the motors so they should be at 0x50 and 0x51.

I'm using two different power supplies for the sensor and ESCs (ESCs are connected to 0v on one battery, and the GND on the ESCs is connected to 0v on the other battery), not sure if this is the issue though.

[Van-man]

[QUOTE=Dorkslayz;48746138]Sure.

I'm building a Quadcopter but i'm having a few issues with communicating with my [URL="http://www.hobbyking.com/hobbyking/store/__39708__Afro_ESC_30Amp_Multi_rotor_Motor_Speed_Controller_SimonK_Firmware_.html"]ESCs[/URL] via I2C. My Raspberry Pi is recognising my MPU6050 sensor just fine, but it's not recognising one of the ESCs and the other is showing up at a completely random address (0x29). I edited and flashed the firmware for both of the motors so they should be at 0x50 and 0x51.

I'm using two different power supplies for the sensor and ESCs (ESCs are connected to 0v on one battery, and the GND on the ESCs is connected to 0v on the other battery), not sure if this is the issue though.[/QUOTE]

I'm pretty damn sure i2c NEEDS a common ground all the way, since it acts as "reference" for the signal.

[rsk_]

[QUOTE=Van-man;48746180]I'm pretty damn sure i2c NEEDS a common ground all the way, since it acts as "reference" for the signal.[/QUOTE]

Hm okay, i'll try connecting the two grounds up.

[paindoc]

[QUOTE=No_Excuses;48744704]Pots shouldn't be a problem unless you hear the noise only when you're adjusting them. Whats the model of the mixer?[/QUOTE]

Behringer X1204USB. I can hear noise when moving the headphone out volume knob, but in general it's fairly noisy.

[No_Excuses]

[QUOTE=paindoc;48746400]Behringer X1204USB. I can hear noise when moving the headphone out volume knob, but in general it's fairly noisy.[/QUOTE]

You should try hooking them up to the control room output or AUX sends and see if you get the same problem.

[paindoc]

[QUOTE=No_Excuses;48747392]You should try hooking them up to the control room output or AUX sends and see if you get the same problem.[/QUOTE]

Good point. I'll have to get an adapter for control room though besides 1/4in balanced, right?

[editline]23rd September 2015[/editline]

or is it unbalanced

[No_Excuses]

[QUOTE=paindoc;48747524]Good point. I'll have to get an adapter for control room though besides 1/4in balanced, right?

[editline]23rd September 2015[/editline]

or is it unbalanced[/QUOTE]

Manual says they're both unbalanced. You'll only get sound out of one headphone but should be able to hear if there's an obvious difference.

[paindoc]

[QUOTE=No_Excuses;48747650]Manual says they're both unbalanced. You'll only get sound out of one headphone but should be able to hear if there's an obvious difference.[/QUOTE]

Right, just saw that myself. I can get an adapter in a but though. Person who gave it to me mentioned it was dusty and could use some TLC, and that channels 1+2 were pretty noisy with bad sliders. I'll most likely have to crack it open myself. Thanks though!

[Papkee]

Behringer products in general are a bit on the noisy side. They're built down to a price and you aren't going to get the same sound quality as a yamaha that costs twice as much.

Other than that, though, I've used the 1024USB for three years now without too many complaints.

[No_Excuses]

My broken power supply came in! I already love this thing - so nice inside. The caps are comically huge for their value. On the right side the blue ones are 560uF @ 200V and the black ones are 1700uF @ 75V. Nearly 4" tall and 1.4" diameter.

[img]http://i.imgur.com/NTClo66h.jpg[/img]

[img]http://i.imgur.com/xRAICQ0h.jpg[/img]

[img]http://i.imgur.com/Au36B5kh.jpg[/img]

The failure mode is pictured in the first pic. Every light comes on BUT the 'Display' button causes an 'OVP Set' indicator to come on, and the decimal under Volts shifts to the left by one place.

Amazingly there's a thread on the EEVBlog forums with this exact unit and problem and they fixed it by replacing a Texas Instruments TMS9981NL microprocessor. Even more amazingly, the seller of this seems to have tried that and sent 3 of the TI micro's with the unit. I will dig into it when I'm not so tired.

[paindoc]

[QUOTE=No_Excuses;48750440]My broken power supply came in! I already love this thing - so nice inside. The caps are comically huge for their value. On the right side the blue ones are 560uF @ 200V and the black ones are 1700uF @ 75V. Nearly 4" tall and 1.4" diameter.

The failure mode is pictured in the first pic. Every light comes on BUT the 'Display' button causes an 'OVP Set' indicator to come on, and the decimal under Volts shifts to the left by one place.

Amazingly there's a thread on the EEVBlog forums with this exact unit and problem and they fixed it by replacing a Texas Instruments TMS9981NL microprocessor. Even more amazingly, the seller of this seems to have tried that and sent 3 of the TI micro's with the unit. I will dig into it when I'm not so tired.[/QUOTE]

Neat! I always love machines designed like this. Its all so cleanly designed and organized and just fun to look at.

I'm thinking of picking up a vintage analog synth on ebay thats listed as broken/for parts and such. Is there anything inanely complex or anything really expensive on old things like this that I should watch out for? I can kludgineer a fix most of the time, and most of these old synths have the best service manuals with parts and locations listed so fixing board components isn't impossible either.

edit:

don't look through sold listings. It may cause feelings of envy that are quite severe.

as in: [url]http://www.ebay.com/itm/Alesis-3630-compressor-/191680782702?hash=item2ca110a16e[/url]

[alealienn]

Need a advise, anyone knows this component? It's from a usb portable ventilator, has 4 pins. There a "277" printed in front of it.
[thumb]https://photos-4.dropbox.com/t/2/AABnVYMZ10pwJP76uNt36WJqoh6gsuLb-AsnNseyr8Ob7g/12/146716695/jpeg/32x32/1/_/1/2/File%209-24-15%2C%208%2028%2003%20AM.jpeg/EI6moXAYhukWIAEgBygH/F80SP_-28NzstSB3PdJPUry-5RNy7sHqEIUgahv5bng?size=1024x768&size_mode=2[/thumb]

[Chryseus]

[QUOTE=alealienn;48751341]Need a advise, anyone knows this component? It's from a usb portable ventilator, has 4 pins. There a "277" printed in front of it.
[thumb]https://photos-4.dropbox.com/t/2/AABnVYMZ10pwJP76uNt36WJqoh6gsuLb-AsnNseyr8Ob7g/12/146716695/jpeg/32x32/1/_/1/2/File%209-24-15%2C%208%2028%2003%20AM.jpeg/EI6moXAYhukWIAEgBygH/F80SP_-28NzstSB3PdJPUry-5RNy7sHqEIUgahv5bng?size=1024x768&size_mode=2[/thumb][/QUOTE]

Can't see picture, try imgur or cubeupload.

[alealienn]

[QUOTE=Chryseus;48751368]Can't see picture, try imgur or cubeupload.[/QUOTE]

[thumb]http://i.imgur.com/9AktWIi.jpg[/thumb]
[url]http://imgur.com/9AktWIi[/url]

[No_Excuses]

[QUOTE=paindoc;48750754]Neat! I always love machines designed like this. Its all so cleanly designed and organized and just fun to look at.

I'm thinking of picking up a vintage analog synth on ebay thats listed as broken/for parts and such. Is there anything inanely complex or anything really expensive on old things like this that I should watch out for? I can kludgineer a fix most of the time, and most of these old synths have the best service manuals with parts and locations listed so fixing board components isn't impossible either.

edit:

don't look through sold listings. It may cause feelings of envy that are quite severe.

as in: [url]http://www.ebay.com/itm/Alesis-3630-compressor-/191680782702?hash=item2ca110a16e[/url][/QUOTE]

It's definitely more risky with older digital gear vs analog stuff. Worst case is having some custom IC fail and not being able to find a replacement. For instance that large white CPU in the second pic appears to be pretty much non-existent, but it seems to only be responsible for the GPIB interface so probably not a huge deal if it fails. Second worst case is probably the EEPROM corrupting somehow. At least with that you could possibly find someone with the same device to dump it for you and send it

[Zero-Point]

[QUOTE=alealienn;48751383][thumb]http://i.imgur.com/9AktWIi.jpg[/thumb]
[url]http://imgur.com/9AktWIi[/url][/QUOTE]

Wanna say it's a hall-effect sensor of some sort.

[alealienn]

[QUOTE=Zero-Point;48751577]Wanna say it's a hall-effect sensor of some sort.[/QUOTE]

It's a UH277 Hall Effect switch. Thanks!

[LoneWolf_Recon]

So the board for my research project, a V-I driver for a software defined impedance analyzer, has arrived and it's looking snazzy (Praise OSH Park):

[img_thumb]https://scontent-iad3-1.xx.fbcdn.net/hphotos-xat1/v/t1.0-9/12009616_10207786724855767_4860955354306976142_n.jpg?oh=6a47fef10f5ed6429a2977ee383f5cd5&oe=5664E08F[/img_thumb] [img_thumb]https://scontent-iad3-1.xx.fbcdn.net/hphotos-xpa1/v/t1.0-9/12039705_10207786726735814_7995007928364943615_n.jpg?oh=b58ee2d6edb3751b9a9ad928b3698a46&oe=56A8477B[/img_thumb] [img_thumb]https://scontent-iad3-1.xx.fbcdn.net/hphotos-xpt1/v/t1.0-9/12039340_10207786729895893_1050717226748635659_n.jpg?oh=492900e37bcd1c5db31d0cf431954d68&oe=56961006[/img_thumb][img_thumb]https://scontent-iad3-1.xx.fbcdn.net/hphotos-xpf1/v/t1.0-9/12046985_10207786727975845_4959059183700529993_n.jpg?oh=dcd87c90fb4c24e31c53d7e5513687b3&oe=569B98FF[/img_thumb]

Bonus: One of the screws for the hinge on my glasses fell out and I lost it. Thus I stuck a resistor lead in it for the time being but later I decided to up the ante :v:

[img_thumb]https://scontent-iad3-1.xx.fbcdn.net/hphotos-xtp1/v/t1.0-9/12019979_10207786852858967_8999335578322258222_n.jpg?oh=e48d8325ea7b634bc95ed5a07a29ede1&oe=565E19D0[/img_thumb][img_thumb]https://scontent-iad3-1.xx.fbcdn.net/hphotos-xtp1/v/t1.0-9/12046859_10207786849258877_5838973579577407785_n.jpg?oh=a4f613b8f73097548ee5573b98d4f019&oe=56A0CC28[/img_thumb]

Its a rather nice close-up inspection light.

[DrLuke]

You're using SMA connectors for DC connectors?
Why not BNC?

[pentium]

HNNNG, that HP power supply.
They made their equipment so beautiful.