jrz126

I'm going to be putting in an order to web-tronics (mainly for the sodium persulfate for etching). I noticed that with a $50 order they will give you a DMM for free ($20 value). I'm in need of a new one, my Sears dmm is falling apart :? It says it "Measures transistor hFE" what does this mean?

With my order right now, sodium persulfate, heatshrink tubing, and 8x10 single sided copper board, I'm up to $27. I could just buy the DMM, but that would put me up to $50 anyways, so I'm looking for some suggestions on what else to order (this is the point of the message, I underlined it so it didnt get confused with my other questions). I'm looking for general stuff that is commonly needed, I already have plenty of caps and resistors that I salvaged from old circuit boards. Any ideas please let me know.

Also, I'm getting a 1kg package of the sodium persulfate crystals. Anyone know the mixture ratio to water? and approx. how many square inches I can etch with it?

Edit: Here's a link to the site http://store.yahoo.com/webtronics/

__________________
Jeff Zimmerman
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

Dean Huster

When you get the persulfate, it should have instructions for mixing with it. When you order, request the Material Safety Data Sheet, just for kicks if nothing else. It's good to have on hand in case of accidental spills, waste disposal or accidental injestion, etc. Etching capability is related to thickness of the copper as well as surface area to be etched. To maximize your etchant, do conservative board layout, making sure that all areas unused for signal traces, etc. are masked over with resist and connected to ground. That way, you're only getting rid of the copper that connects traces to stuff they aren't supposed to be connected to.

You can always buy more copper-clad board for your next PCB projects. Tinnit powder is good for tinning the etched board, but be aware of the fact that it has a very limited shelf life after mixing. It precipitates out like crazy. Warming up stored solution may help.

Even though you may have lots of second-hand resistors, resistors are cheap, and it doesn't hurt to start a program of buying bulk packages (200 count) of the most-used values. If you're getting into more precision electronics such as A/D converters or test instruments, you'll start wanting some 1% tolerance resistors. You can start by buying smaller packs of these (10 count or 20 count) in values like 100, 1K, 10K, 100K, 1M and then later expanding the values to yield voltage dividers of x2, x3, x4, x5, etc.

Although you may have a good stock of second-hand caps, you never have enough 0.1µF and 0.01µF disc ceramic types ("M" or "Z" tolerance) for digital bypassing applications where you ought to have one cap per chip in your projects.

Dean

__________________
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

zachtheterrible

Hi jrz, Yeah, buy a bunch of caps. Get values that are often called for in schematics. I just bought a ton of caps, and im glad I did. these are some of the values i ordered. i use em alot

.1uf, .01uf, .001uf, .47uf, .047uf, .0047uf, .22uf, .022uf, .0022uf. I would also buy a package of capacitors in the pf range, like an assortment. these are indespensable if u do anything with radio. Buy a bunch of 2n3904 and 2n3906 transistors, again, i use em a ton. Buy a bunch of LEDs, they're fun to play with and make flashlights. umm, audio amps maybe. Maybe some adjustable caps. Some POTs. Electret microphones, etc etc. Or you could probly buy urself a power supply.

thats just an overview of wut ive got in my electronics kit. i do a lot with analog and radio and stuff. i heard u like digital, so im sure u can buy some o that stuff.

A measure of Hfe is the gain on the transistor.

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I'm no electronics god, i just talk too much.

evandude

they have LEDs... $1.50 for 100. can't beat that deal.

I bought one of their soldering stations for $35. really nice especially for the price, believe they were made by hakko, who make some really nice ones.

i really like the sodium persulphate, it's good stuff.

i mix 4 teaspoons with 1/3 cup hot water in a ziplock baggie and it's perfect for etching smaller boards.

the DMM is really cheap, i got it with my last order. it may not be worth your while trying to up your order to get it. it's NOT auto-ranging so you have to switch ranges manually, and it just looks and feels cheap. the probes are crap, and the thing is HUGE (it makes my sears DMM look really tiny)
basically you get what you pay for. i guess it would be good to have as a backup in case you misplace your good one someday...

zachtheterrible

If you're looking for a decent VOM, harbor freight is having a sale on a one made by cen-tech. I have one, and it works just great, accept i blew the amperage testing feature which is y im gonna go buy one. They're only $3.99. It has dcv, acv, dca (it goes up to 10A), hfe, diode check, and resistance. And its yellow :lol:

__________________
I'm no electronics god, i just talk too much.

jrz126

maybe a dumb question, but did you check the fuse for the amp meter? (if it has one? being that cheap it might not.)

__________________
Jeff Zimmerman
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

zachtheterrible

yea, the fuse was fine.

__________________
I'm no electronics god, i just talk too much.

jrz126

Hey Evandude, is this the one that you bought? http://store.yahoo.com/webtronics/cispdeesdsas.html?

If not, does it look like a good deal?

__________________
Jeff Zimmerman
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

plot

potentiometers are always nice to have on hand. as is wire-wrap wire if they have it (it's 28guage wire i think).

maybe a solder station.... diodes always come in handy, a few enclosures for projects are always nice to have around.

need a new, or an extra breadboard?

or get a couple of velleman kits to play around with.

jrz126

Wait a minute, evandude, is this the same soldering station that you are trying to repair in that other post :?
Maybe I should buy another breadboard, I only have a small one left, I have a big one and another small one in my trunk for my led circuit. and I wont get those back until I make a printed board.

__________________
Jeff Zimmerman
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

evandude

yep, that's the one i bought, and that is also the one that ceased to work after only a few hours of use. I'm still working on fixing it.

the only reason i recommended it is because i assume i am just unlucky and got a dud. as far as i can tell, the station is the same as the hakko 936, which is a VERY highly recommended station costing about 3 times as much. and circuit specialists says these stations are manufactured by another company, specially for them.
http://www.lico.at/productionsale/DS..._Hakko_936.JPG
that just looks FAR too similar to be a different product.

anyway, i'm emailing hakko to see if they can offer any insight on the matter.

if you are strapped for cash, then you should probably avoid it, but if you can afford to take the chance then i would go for it, the price is excellent; and to be fair, they DID offer to replace the unit, free of charge. I just didn't want to pay to mail it back to them, or wait around to receive the replacement.

plus, by now i already have a COMPLETE schematic of the unit, and I like the idea of being able to fix it again if it ever breaks in the future. granted, it has taken me hours of work to go from looking at the PCB, to drawing a schematic, but nobody else will have to suffer with it now that i've done it :wink:

plot

i second the hakko 936, those are extremely nice temperature controlled soldering stations that run about 70-80$ i think...

evandude

i just heard back from hakko. these web-tronics irons are in fact just foreign ripoffs of the hakko 936. oh well, at least they're built pretty similarly. and i can say that i was very impressed with its performance. it heated up in about 30 seconds or less, as compared to a couple minutes for my weller iron. and it seemed fine at holding its temperature.

jrz126

I work at GE transportation systems in Erie, and they have outsourced some stuff to "save" money, by the time we get the product from them and realize that it is compleatly wrong, and we have to have some guys repair it. It seems kinda pointless.

Have you got it fixed yet?

__________________
Jeff Zimmerman
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

evandude

well as i see it the worst case is that i replace the 2 IC's and the triac. that will just take an order from digi-key. hopefully tonight or tomorrow i will get a chance to mess with it some more and see if i can further narrow down what isn't working. my guess is that either the triac is dead, or the op-amp chip, either of which would be easy to replace... i'll keep you guys posted i guess