Search found 2766 matches

by haklesup
Wed Mar 19, 2003 10:34 am
Forum: General Discussion
Topic: Differences in transistors
Replies: 7
Views: 1178

Re: Differences in transistors

Even within the same manufacturer, lot to lot differences exist. This is why it can be a challenge to build a differential amplifier out of discrete components. People pay a premium for matched pairs of transistors or even pairs mounted in the same package.<p>Look at the Electrical Characteristics o...
by haklesup
Tue Mar 18, 2003 5:07 pm
Forum: General Discussion
Topic: Differences in transistors
Replies: 7
Views: 1178

Re: Differences in transistors

I believe they are. Both part numbers cross reference to the same NTE rfeplacement part number www.nteinc.com/specs/100to199/pdf/nte123ap.pdf <p>the 2N prefix is a standard from JEDEC and is much more common http://www.chipdocs.com/pnsearch/search.html?okwd=MPS3904&partid=11732&ReR=GG but the MPS is...
by haklesup
Tue Mar 18, 2003 4:34 pm
Forum: General Discussion
Topic: CCD switching noise?
Replies: 3
Views: 673

Re: CCD switching noise?

The answer to your question is deeply rooted in the methodologies used to design IC chips. The noise you imagine should not exist in a proper design. <p>Much effort goes into simulating the electrical signals that are present in the circuit. The models that go into Spice and VHDL are based on the la...
by haklesup
Tue Mar 18, 2003 10:47 am
Forum: General Discussion
Topic: Telephone Jack
Replies: 11
Views: 1253

Re: Telephone Jack

What you want is a Molded Modular connector for an RJ-11 plug. The dual ones are just 2 plugs molded into the same part for convenience but there are no shared pins between them usually they are 2 seperate jacks and you may just as easily use two singles in your project. <p>Normally they (Red and Gr...
by haklesup
Mon Mar 17, 2003 4:36 pm
Forum: General Discussion
Topic: I'm new to this.
Replies: 4
Views: 854

Re: I'm new to this.

As a person new to electronics, my advice is to step back look at what others are doing (and how they are doing it), pick something of interest and create a project based on that interest.<p>There are a lot of good introductory and or general information books to get you started but depending on you...
by haklesup
Fri Mar 14, 2003 11:16 am
Forum: General Discussion
Topic: What is a Journeyman Electrician ?
Replies: 4
Views: 1011

Re: What is a Journeyman Electrician ?

That's essentially it but in addition there are classes given by the union that must be completed and a minimum number of hours that must be worked during those 4 years. It can take longer for some people. This is true of most trades. Getting work at the union hall can be a long wait these days as m...
by haklesup
Fri Mar 14, 2003 11:05 am
Forum: General Discussion
Topic: Current logging
Replies: 3
Views: 726

Re: Current logging

The control board in a UPS does most of these things. Measure Frequency, Voltage of mains and output, Load usage and a few other parameters about the battery like temperature and DC voltage as well as charge/discharge current etc. and they already have a Serial or USB interface.<p>I can't remember w...
by haklesup
Fri Mar 14, 2003 10:56 am
Forum: General Discussion
Topic: computer contol
Replies: 6
Views: 1032

Re: computer contol

A lot depends on the type of control your RC car needs. Most cheap toys are simply 4 channel on-off type transmitters. The right, left, forward and reverse channels are either on or off. this is the easier case since all you need to do is use an interface (your choice, USB, Serial, Parallel) which g...
by haklesup
Thu Mar 13, 2003 4:53 pm
Forum: General Discussion
Topic: Tips for removing residual solder?
Replies: 7
Views: 1115

Re: Tips for removing residual solder?

More precisely, the gold forms a thin intermetallic layer that is an alloy of the two metals (actually 3 or more since solder is already an alloy). The thickness of this layer depends on the grain size and excat composition of the base metal (gold or gold alloy) and the temperature it was applied et...
by haklesup
Thu Mar 13, 2003 3:35 pm
Forum: General Discussion
Topic: Tips for removing residual solder?
Replies: 7
Views: 1115

Re: Tips for removing residual solder?

Assuming the base metal is Gold (although Copper should give similar selectivity)Copper does etch more readily than Gold both are destroyed by anything with Nitric acid in it.<p>A solder etch bath can be made from 75%(by Vol) Acetic Acid and 25% (by vol) Hydrogen Peroxide (H2O2)(30%). Now that perox...
by haklesup
Mon Mar 03, 2003 5:47 pm
Forum: General Discussion
Topic: generate sensor signal
Replies: 9
Views: 1872

Re: generate sensor signal

"I've heard mechanics say, unplugging sensors for diagnostic purposes was poor diagnostics."<p>It depends on what you are doing. For example if you have a very poorly running engine presumably due to a faulty sensor, then unplugging the bad one may have no effect because it is already bad, unpluggin...
by haklesup
Mon Mar 03, 2003 2:04 pm
Forum: General Discussion
Topic: generate sensor signal
Replies: 9
Views: 1872

Re: generate sensor signal

A half amp (500mA) may be an acceptable current if you just plan to use it intermittantly. I was thinking you wanted a perminant connection to the battery and therefore a low current would prevent premature discharge of the battery while you were parked.<p>I don't know about the car tech's procedure...
by haklesup
Sun Mar 02, 2003 12:27 pm
Forum: General Discussion
Topic: Pulses to control stepper motor
Replies: 11
Views: 1825

Re: Pulses to control stepper motor

You want a divide by 4 digital circuit. You can make one using two JK flip flops (or one Dual). Use a 4027 and you won't have to worry about supply voltage as much. 40xx series logic can run from 3V to 15V<p>Make sure that the pulses from your engine sensor are same or lower voltage than the logic c...
by haklesup
Sun Mar 02, 2003 12:14 pm
Forum: General Discussion
Topic: Daytime running lights
Replies: 1
Views: 865

Re: Daytime running lights

A newer car may have a place to plug a module directly in without extra wiring (as is required in some markets like Canada). Check with the Dodge dealer for the part.<p>Here is a link to a basic module for $10 you can install yourself. http://www.jcwhitney.com/productnoitem.jhtml?CATID=5139&BQ=jcw2....
by haklesup
Sat Mar 01, 2003 11:44 pm
Forum: General Discussion
Topic: small amp ?
Replies: 5
Views: 954

Re: small amp ?

If the biulding is entirely covered in metal than that is your problem. You are in a fariday cage. You can have the best antenna on a sensitive radio but it is still shielded from the signal. You need to get the antenna outside. <p>Try a simple FM Dipole (T shaped wire) and hook it up to the spring ...