T&L Publications

Depends upon the op amp type. The LM324 recommended earlier is not R-R (Rail to Rail). It can't source more than 3.5V on a five volt supply. Yes, but let's not lose sight of the reason he was asking: the question was "if the gain is 1.5 and the input voltage is e.g., 4V, will the output go abo...

Bigglez:
I don't think your diagram came through OK. Looks like it's missing a few R's & C's. Why do you think the gauge needs a DC bias?

toolmaker:
That is correct: the opamp will be limited to its power supply rails (0-5V).

I love auctions!!! I'm pretty well stocked in terms of electronics stuff, but I used to go to machine shop auctions. Great way to pick up stock metal that's normally expensive, esp. after shipping charges are factored in. I also now have enough endmills to last me a lifetime! I still get emails abou...

Let's start simple and get more complex from there, OK :-) First, just the multiplier. Like Bigglez said, you need an opamp. To be sure that you don't exceed 5V at the output the best way is to make your power supply voltage 5V, so you need a voltage regulator. 7805 regs are cheap and easy to use. A...

Hi, We have a lot of cranks popping up around this area...all different kinds. I'm too lazy to crank so i stick to the battery ones. Not to worry. On another forum someone posted that they bought one of these crank flashlights and opened it up. The crank did nothing and the LED was powered by a bat...

Bought about 25 pieces of 2x40 header pins, gold plated for $0.17 each from BG Micro a few months ago. I made a little tool to cut them at the "snap indents." I use them to make AVR ISPMk1 headers (2x5) Can't get much cheaper than that; I should have just gotten a round 100 and had close t...

Well, if you're new to electronics, I'd start with a battery powered version to get experience. Playing around with 120VAC can be dangerous. How I'd do it: forget the alarm clock; get a plug-in timer module. They make them digital or with little pins to set the time and they will turn a circuit on/o...

The end panel part # is: SR2003-DB9B-ND
THe boxes vary from 4x2x.8 to 7x5x1.6. e.g., #SRA20A-ND

MrAl wrote:Hi Eng,

Really, how big are they? (LWH)

I just noticed that you can also get enclosures with D-sub cutouts already in them reasonably priced: about $10 with db9/25 end panel from Digikey.

How much do you want to pay? I have a DB25 punch that works great, but cost about $150. I've also tried square punches, but didn't have much luck with them. Still $$$ These days I'm lucky enough to have a small benchtop milling machine that I was able to justify the cost for since it sped up a job I...

http://www.newark.com/21H6682/industria ... -q45bw22lv

Available on surplus market much cheaper!

If the float was the problem it's quite easy to get float switches ready made. They cost from about $8 and up at most electronics distributors: Digikey, Newark etc. You can also buy liquid level alarms: We have one on the septic system. I tried using an led light hook up to an improvised float but t...

Why do you need to know when it goes on? Is it sufficient to just know when it *should* turn on? Can you monitor the state of a level switch that's at the same height as the pump's? That would be easier than monitoring the pump itself.

The really funny thing is that I bowed out of this thread pretty early. In fact when it just came back up I had no recollection of starting it :-) Anyway, with PC boards so cheap now (I found a site that will do 100 boards of about 1.5sq in for $70!!!), I don't bother making my own any longer. Just ...

Nah, if you want a real trick, put one of those passive anti-theft devices in his wallet. I used to always set off alarms in certain stores. Not all, but after a while I could predict which ones. I specifically remember being in Seattle on vacation and telling my wife as we walked into a Barnes&...