Electrical Engineering V3 - Developers

[QUOTE=RoflKawpter;49741550]HELLO FOLK FRIENDS I'd like to upgrade the firmware on my monitor (see here: [url]http://www.blurbusters.com/benq/diy-firmware-upgrade-for-benq-z-series/[/url]) as apparently the new firmware is absolutely crap-tacular! I don't want to buy the MSTAR ISP Adapter cause LOTS of money. I'd like to attempt to make this adapter! [url]http://forums.blurbusters.com/download/file.php?id=10[/url] I do have some experience soldering, making circuits, etc. I have the resistors and I think I have the transistors (I'd have to check my supply bin) However, I'm super sketched out with making this because I'd rather not fry my expensive monitor. I'd either like some kind of guidance on how to make this (interpretation of the circuit) or maybe I can just ask someone in Canada (I live here) to make one and ship it to me? Would anyone just give me a general idea of how dodgy it would be if I was to make something like this? It doesn't seem really complicated, but I'd like a second opinion on how I should tackle this. Thanks[/QUOTE] Oh wow, firmware updating a monitor over the I2C line meant for the computer to get its supported frequency and resolution. If the updating procedure were a little more open, then I bet a arduino (or clone) could do it, along with a *nix computer.

Courtesy of Cakebatyr :v: [img_thumb]http://i.imgur.com/p65PrFl.png[/img_thumb]

[t]http://i.imgur.com/BHG29Zn.png[/t] Cascode amplifier PCB, because 10 MHz+ on a breadboard is a terrible idea. Going to use some nice BFP420 transistors on there later once I'm happy with performance.

I got Chryseus stumped on this one. [IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/pin10.png[/IMG] IN2 should be 5v. Instead it's 2.2v. All components read within tolerance. :huh:

Ask me next year once I've started all my EE classes and I might be able to help [editline]16th February 2016[/editline] But probably not because I still won't know shit

[QUOTE=pentium;49750529]I got Chryseus stumped on this one. -img- IN2 should be 5v. Instead it's 2.2v. All components read within tolerance. :huh:[/QUOTE] Sorry if i'm wrong, but i'm in my first year of EE classes, so i'll make a guess. What if you flip the diode around? Right now, the current has to flow through the diode and the resistor, and since the diode is blocking in it's current position it has to go through the resistor, causing a drop in voltage. I am more than likely wrong, feel free to correct.

[QUOTE=pentium;49750529]I got Chryseus stumped on this one. [IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/pin10.png[/IMG] IN2 should be 5v. Instead it's 2.2v. All components read within tolerance. :huh:[/QUOTE] Maybe if you drew a proper schematic it would be easier to see what's going on.

[t]http://i.imgur.com/yshtVPc.png[/t] Cookies to anyone who figures out how the inverting input gets pulled down to 2.1V.

R2 and ESR of C1 creating a voltage divider?

[QUOTE=papkee;49752611]R2 and ESR of C1 creating a voltage divider?[/QUOTE] The capacitor would have to be totally screwed to have any effect on the voltage, 2.1V is on the good drive that works which is why I want to find out how it gets down to 2.1V. Every passive around it has been checked, including a new diode and capacitor and even a new comparator.

[QUOTE=DrDevil;49752074]Maybe if you drew a proper schematic it would be easier to see what's going on.[/QUOTE] I could always use CDC's schematic which is for another model drive if you like. :v:

[QUOTE=Chryseus;49752578][t]http://i.imgur.com/yshtVPc.png[/t] Cookies to anyone who figures out how the inverting input gets pulled down to 2.1V.[/QUOTE] I guessed that since the LM319 is a BJT comparator (FET Master Race), it might have significant input bias/offset current. But the [URL="https://www.fairchildsemi.com/datasheets/LM/LM319.pdf"]datasheet[/URL] ([URL="http://www.ti.com.cn/cn/lit/ds/symlink/lm319-n.pdf"]s[/URL]) have tiny input bias/offset current. So much so that the voltage drop across R2 (after transients have been accounted for C1), would only be 12.3mV worst and ~1.2mV best. Next guess is the common mode isolation between the inputs, but the datasheets don't list anything about CMRR, etc. However tracing the function diagram (pages 2 or 10, depending upon datasheet), it seems to have a rather poorly designed input stage than most DAs. There's no proper current sources to bias/balance the input BJTs and their Ree (R25) seems pretty small. I want to take a stab and say that Vref/IN+ is what is pulling IN- down to 2.1 as the input BJTs don't seem to be well isolated from each other but its a guess. Maybe try another BJT/Open Collector output comparator like the LM339?

Not a bad idea but I don't think HP would design a circuit that takes advantage of unusual comparator behaviour, the comparator on the bad drive behaves as expected (- rises to ~5V), the good drive is the one with the unusual readings, I'll get mips to recheck maybe he accidentally measured the non-inverting pin twice. :unimpressed:

[QUOTE=Chryseus;49753881]Not a bad idea but I don't think HP would design a circuit that takes advantage of unusual comparator behaviour, the comparator on the bad drive behaves as expected (- rises to ~5V), the good drive is the one with the unusual readings, I'll get mips to recheck maybe he accidentally measured the non-inverting pin twice. :unimpressed:[/QUOTE] Nah, apparently I was mixing up my components. :suicide:

[t]http://i.imgur.com/fbjYYfU.png[/t] Comrades I am ready for world war 3.

Quick question I have the following lying around : [thumb]http://i.imgur.com/jpjAOg3.jpg[/thumb] Its a button with socket for 230v, connected to a 230v to 24v 290ma transformer which is connected to a full wave rectifier. Now I want to use this : [URL]http://www.dx.com/p/20083-adjustable-power-supply-voltage-regulating-reducing-module-blue-black-255394#.VsRf3PnhCUk[/URL] To step down the voltage to 7-12v ? and connect it to the green cable to power my arduino, would this work or would I need some smoothing caps first, or will it all go BANG. Secondly if this works could I draw 2 more wires from the 230V socket into the relay to power the 230v AC lights in parallel that you see in the background? Edit: Read that the input voltage is not 5v but 6v-20v and recomended 7v-12v, would that mean that 12v is ideal ?

[QUOTE=quincy18;49758634]Quick question I have the following lying around : [thumb]http://i.imgur.com/jpjAOg3.jpg[/thumb] Its a button with socket for 230v, connected to a 230v to 24v 290ma transformer which is connected to a full wave rectifier. Now I want to use this : [url]http://www.dx.com/p/20083-adjustable-power-supply-voltage-regulating-reducing-module-blue-black-255394#.VsRf3PnhCUk[/url] To step down the voltage to 5V and connect it to the green cable to power my arduino, would this work or would I need some smoothing caps first, or will it all go BANG. Secondly if this works could I draw 2 more wires from the 230V socket into the relay to power the 230v AC lights in parallel that you see in the background?[/QUOTE] It looks to have the smoothing caps on it already but it should not hurt to att on on the output of the rectifyer. Im sure that you could also hook those light up also but just make sure to properly hook them up. Some thing like [url]http://www.ebay.com/itm/1Pcs-WAGO-Cable-Spring-Compact-Connector-3-Wire-Lever-Terminal-Block-new-CAR-/281816140942?hash=item419d8d0c8e:g:p0wAAOSw9r1WCjzM[/url] works wonders for wiring

I wanted to etch a board fast, but then I got sidetracked into playing with my power supply. Long story short, I remembered that galvanizing, electroplating etc. exist, so I connected my copper clad board to the positive supply, a piece of wire into ground, dunked the end of the wire, and the part of the board with my design on it, into the etchant. Man, that etched real fast. I gave it 1A constant current, and I ended up with a piece of wire with copper coated on top of it. A lot of copper. But it doesn't stick, because I didn't give it any time etc., I think it has to be a slow progress and way more controlled for proper coating, so it just broke off the wire. But it etched the board really fast, and I ended up with basically no underetch.

I used to zinc plate pennies with a phone charger and vinegar. Was fun.

When you're plating things you also need to factor in the electronegativity of the elements you're plating. From what I've been told anything more than a difference of around one makes it a hell of a lot harder. Surface prep is also critical; any grease or oil or really anything at all will make the plating rub right off.

[QUOTE=nikomo;49760333]I wanted to etch a board fast, but then I got sidetracked into playing with my power supply. Long story short, I remembered that galvanizing, electroplating etc. exist, so I connected my copper clad board to the positive supply, a piece of wire into ground, dunked the end of the wire, and the part of the board with my design on it, into the etchant. Man, that etched real fast. I gave it 1A constant current, and I ended up with a piece of wire with copper coated on top of it. A lot of copper. But it doesn't stick, because I didn't give it any time etc., I think it has to be a slow progress and way more controlled for proper coating, so it just broke off the wire. But it etched the board really fast, and I ended up with basically no underetch.[/QUOTE] If you want to etch super fast, you should try 35% H2O2 with 30% HCl ( % purities, not proportions ). I really have no idea why people are even touching ferric chloride. It is also reusable and has a decent shelf life if you keep adding H2O2 once it gets slow. As for disposal just dump it in the closest river. ( It might be possible to make the liquid safe for disposal by adding baking soda. It should react with the remaining HCl and precipitate any aqueous copper ).

[QUOTE=alexaz;49764682]If you want to etch super fast, you should try 35% H2O2 with 30% HCl ( % purities, not proportions ). I really have no idea why people are even touching ferric chloride. It is also reusable and has a decent shelf life if you keep adding H2O2 once it gets slow. As for disposal just dump it in the closest river. ( It might be possible to make the liquid safe for disposal by adding baking soda. It should react with the remaining HCl and precipitate any aqueous copper ).[/QUOTE] I can't get H2O2 in concentration above 5% thanks to people of the genuine 'aloha snackbar' variety. Apparently, mixed with synthetic fertilizer makes it into bomb material.

[QUOTE=Van-man;49764700]I can't get H2O2 in concentration above 5% thanks to people of the genuine 'aloha snackbar' variety. Apparently, mixed with synthetic fertilizer makes it into bomb material.[/QUOTE] At least in the Netherlands it's legal to own (and make it yourself) until the 2nd of March, 2016. All you have to do is boil the water out, or put it in a freezer and take the ice crystals that form on the top off. What you take out is pretty much pure water and it's easy enough to calculate the concentration

[QUOTE=Goz3rr;49764850]At least in the Netherlands it's legal to own (and make it yourself) until the 2nd of March, 2016. All you have to do is boil the water out, or put it in a freezer and take the ice crystals that form on the top off. What you take out is pretty much pure water and it's easy enough to calculate the concentration[/QUOTE] Any ideas where I can find H2O2 in the Netherlands though? I used to live in Lithuania where home improvement stores actually carry a decent variety of consumables and tools cheap, but since I am now studying in the Netherlands things appear to be more complicated. I went to GAMMA and the prices are fucking insane. 4 euros for a 8 mm wrench ( where in Lithuania decent quality small wrenches cost 70 cents tops ). I also was looking for some acetone and was amazed when I was told that they don't have acetone. A god damn 2000 square meter home improvement store does not sell acetone.

[QUOTE=alexaz;49765412]Any ideas where I can find H2O2 in the Netherlands though? I used to live in Lithuania where home improvement stores actually carry a decent variety of consumables and tools cheap, but since I am now studying in the Netherlands things appear to be more complicated. I went to GAMMA and the prices are fucking insane. 4 euros for a 8 mm wrench ( where in Lithuania decent quality small wrenches cost 70 cents tops ). I also was looking for some acetone and was amazed when I was told that they don't have acetone. A god damn 2000 square meter home improvement store does not sell acetone.[/QUOTE] Try the Etos, it sells aceton for sure. Make sure you pick up the pure one and not the nail polish remover. I think it was 1.60-1.80 per 100ml

[QUOTE=alexaz;49765412]Any ideas where I can find H2O2 in the Netherlands though?[/QUOTE] It'll probably be cheapest and easiest to buy it online, you're allowed to buy up to 12% as a consumer

Hydrogen peroxide is hella expensive over here, I couldn't find any decent source when I looked. Hydrochloric acid is also a real bitch to deal with, sodium peroxydisulfate and hot water is much nicer.

Here's a good way to [URL="https://www.youtube.com/watch?v=xvYeefmbmZI"]concentrate hydrogen peroxide[/URL]. Mostly you just boil away the distilled water component to leave the H2O2 behind.

[QUOTE=alexaz;49765412]Any ideas where I can find H2O2 in the Netherlands though? I used to live in Lithuania where home improvement stores actually carry a decent variety of consumables and tools cheap, but since I am now studying in the Netherlands things appear to be more complicated. I went to GAMMA and the prices are fucking insane. 4 euros for a 8 mm wrench ( where in Lithuania decent quality small wrenches cost 70 cents tops ). I also was looking for some acetone and was amazed when I was told that they don't have acetone. A god damn 2000 square meter home improvement store does not sell acetone.[/QUOTE] Welcome to my biggest frustration when doing DIY stuff here: shit seems impossible to get and the stores suck huge dick. For small tools I suggest ordering from china via something like dealextreme or ebay.

God damn. Bought an adapter for a small guitar amplifier. Turns out the jack is too small [t]https://upload.wikimedia.org/wikipedia/commons/6/68/Photo-RoundPowerConnectors.jpg[/t] I have the one with yellow, I need to one on the far right. Could I possibly just cut off the jack and solder the correct one on? Thoughts? I don't do a lot of electrical engineering anymore. :v: