Electronics Forum / Electronics / June 2006

I bought an AC piezo driver (0-20V, bandwidth>100kHz).
I also have a DC piezo driver (0-150V).
I want to build something that can add those two signals.
I tried to use a high-power, ultra-fast OpAmp to make a simple adder.

I wonder if anyone can help with a manual/data for a Sanwa Transistor
Checker Model AT-1
Thanks
Peter

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When I was a youngster, I spent many a happy childhood hour tearing
apart old radios and TVs, messing about with bags of surplus transistors
bought at Radio Shack, and poring over old issues of "Elementary
Electronics" trying to make sense of the tutorial series.  My pride and

Hi everyone, we had a 6 hour blackout here today and when the power came
back on all the electronic stuff in the house (and there is a lot of it)
came back on just fine, except my sons unit (Dead as a maggot), I vaguely
remember a few years ago having the same problem with a ...

Looked at several Motorola SM56 modems an all have the same fault-non
infinite resistance at line jack which  causes them to take over the
line once the line is plugged, so none of  the telephones can be used!
Checked the MOV and it is ok and there is no relay on modem !(at least

**  They still keep up with the times ...
http://tinyurl.com/g5s5b
.......   Phil

I am looking to build a Sonar-system that allows me to measure depth
(under water). I found some references to National Semiconductor's
LM1812 but this chip is no longer available, is there a equivalent or
replacement?

I am seeking a reverse switching relay so that when the first circuit
is switched on, it switches another circuit off? Also when the first
circuit is switched off, the other circuit is switched on. I am
thinking of using it with 12 volts.

My friend has just bought an LCD TV with a built in STB Digital tuner. She's
also got Foxtel, a DVD player, a VCR, an AV transmitter to send the Foxtel
to other rooms etc. The etc. includes a Stereo, Tuner, Casette Player,
Record Player etc. but they're not important right now.

How long can you expect programs, burnt into the flash ram of
microprocessor chips, to last?
If I make up a piece of equipment based on say, an ATMEL AT90S2313 chip
how long could this stay in service before getting "soft" bits?

I just assembled a circuit which has a transistor to switch the coil on
a relay (driven from logic level of microcontroller).  The transistor
is a general purpose TO92 package, 0.5 A switching type (like a 2N2222
or similar).

I scored two NEC projectors today for $25, these are a
Multisync MT830+ and a Multisync MT1030+. They were sold
as having a faulty power supply that would only run in
standby mode, but turned out to be the air filter switch

Pair of 1000w 12" subs in a sealed 72ltr enclosure, both subs are
partitioned off from one another, so its like 2 enclosures in one.
constructed of 32mm MDF professionally, carpeted.   subs are dual voice coil
Lanzar Vibe 12" subs with poly cones.

I've a voltage change 3-4 Volts which I need to change into a 0 to 4
Volt signal.
I have used an inverting op-amp with a virtual ground to give a
cracking result but unfortunately the voltage is going the wrong way