Search found 235 matches

by Dimbulb
Mon Jun 11, 2007 11:38 am
Forum: General Discussion
Topic: How do I Fine tune a 78L05 ?
Replies: 50
Views: 12078

all good ideas but staying with the original problem for now and yes my meter can do 5 places. If I use a 10K ohm for R1 .1 ohm resistor for R2 and modify the formula 4.995+(4.995/10000+.05)*.1 = 5.00004995 theoretically a small fractional resistor in this senario should trim the 78L05 using the dat...
by Dimbulb
Sat Jun 09, 2007 10:23 pm
Forum: General Discussion
Topic: How do I Fine tune a 78L05 ?
Replies: 50
Views: 12078

How do I Fine tune a 78L05 ?

Does anyone have experience adjusting a TO-92 78L05 ? I would like to change the output 4.995 V to 5.000 V at national semi: http://www.national.com/ds/LM/LM78L05.pdf under Typical Applications the second example is given. with a formula VOUT = 5V + (5V/R1 + IQ) R2 5V/R1 > 3 IQ, load regulation (Lr)...
by Dimbulb
Sun May 13, 2007 8:33 am
Forum: General Discussion
Topic: air conditioner pre cooler
Replies: 42
Views: 13679

What about using an automobile radiator to pre-cool the air.
by Dimbulb
Tue Feb 27, 2007 10:30 pm
Forum: General Discussion
Topic: Constant PH Monitoring
Replies: 5
Views: 2592

I like accuracy, so as to clean, neutralize and calibrate the probe to a known buffer standard. I want to run a test so the results could be reproduced over and over. firstly If all I need is a garden variety meter to do this then ok, so it depends on what you are doing. having said this if continui...
by Dimbulb
Wed Oct 18, 2006 10:31 am
Forum: General Discussion
Topic: Radio Shack fires person with experience in Electronics
Replies: 23
Views: 7537

It is shameful that Radioshack inventory is not what it used to be. I think most of us have purchased a good pile of parts over the years. RS corporate does'nt conciders our past sales as significant enough to continue the parts and service as it did in the past. The new owners of RS stores should h...
by Dimbulb
Sun Feb 26, 2006 9:54 am
Forum: General Discussion
Topic: LM358 variable voltage ?
Replies: 4
Views: 1023

Re: LM358 variable voltage ?

The stability and precision of the op amp is needed. it uses a reference of 0.002 volts. My question is to gather useful hints in making a 1X to 250X single supply LM358 instument amplifier using batteries. The 5 volt supply is regulated and the reference is well regulated. I am not sure if self adj...
by Dimbulb
Sat Feb 25, 2006 8:03 pm
Forum: General Discussion
Topic: LM358 variable voltage ?
Replies: 4
Views: 1023

LM358 variable voltage ?

I am interested in making a battery powered
voltage source.

I want to use an LM358 powered by four AA batteries.

I have a stable 0.002 Volts reference.
How can I get a variable output from
.002 to 5.00 volts ?

Thankyou
by Dimbulb
Sat Feb 04, 2006 7:24 am
Forum: General Discussion
Topic: "Perfect" LED current limiting challenge
Replies: 255
Views: 56088

Re: "Perfect" LED current limiting challenge

The project should have been described as an efficient Pic Stamp based PWM 20mA led controller. I still wonder why you did not make clear what you really wanted to do and why it was kept secret. For me it is frustrating when the scope of a project is not disclosed and good ideas deemed irrellavant. ...
by Dimbulb
Tue Jan 31, 2006 11:37 pm
Forum: General Discussion
Topic: precise location in space
Replies: 32
Views: 8989

Re: precise location in space

If you have to monitor him that close he should'nt be driving. He is not a dog.
by Dimbulb
Sun Dec 25, 2005 6:35 pm
Forum: General Discussion
Topic: "Perfect" LED current limiting challenge
Replies: 255
Views: 56088

Re: "Perfect" LED current limiting challenge

The project may need to address two battery conditions: 1. Condition: The battery voltage IS adequate lets assume We are satisfied with the 3.6 volts is 89% efficient [3 x 1.2 volt cells] 2. Condition: The battery voltage IS NOT adequate. propose a scheme to make the batteries useable right down to ...
by Dimbulb
Thu Dec 15, 2005 6:20 pm
Forum: General Discussion
Topic: use of electricity
Replies: 5
Views: 1021

Re: use of electricity

At the present time the larger percentage of work done man made electricity derives from cutting magnet lines ( not sure what the by-product is honestly) and chemical reactions (the crude inside a battery and spent rods. Also static electricity and solar cells are small percentage. In saying that Th...
by Dimbulb
Mon Dec 12, 2005 8:33 pm
Forum: General Discussion
Topic: simulating an LM431
Replies: 3
Views: 959

Re: simulating an LM431

Thanks, I made a copy of LM117 and replaced the model data with your model data and remamed it LM431. I will try it out as time allows.
thanks for your help!
by Dimbulb
Sun Dec 11, 2005 9:39 pm
Forum: General Discussion
Topic: "Perfect" LED current limiting challenge
Replies: 255
Views: 56088

Re: "Perfect" LED current limiting challenge

If a series resistor used as a current limiter in a simple design gave energy in the form of light then the led current could be reduced.
If a new battery design had current limiting charecteristics and voltage for leds then the scheme should be new and useful.
by Dimbulb
Sun Dec 11, 2005 11:16 am
Forum: General Discussion
Topic: simulating an LM431
Replies: 3
Views: 959

simulating an LM431

I am using multisim (electronic workbench)
and would like to simulate an LM431.
Would anyone have a working example I could
try ? Thanks
by Dimbulb
Sun Nov 06, 2005 7:52 pm
Forum: General Discussion
Topic: voltage and current regulation
Replies: 15
Views: 8248

Re: voltage and current regulation

several terms current limiter, current limiting regulator and current source regulation are related. If I understand correctly Finding an appropriate semiconductor scheme involves thermal charecteristics so the device being powered can have ultra stability. This is the amount of dissipation required...