Search found 218 matches

by k7elp60
Sun Jan 13, 2008 7:01 pm
Forum: General Discussion
Topic: Need a simple circuit for detecting a TTL-level square wave
Replies: 7
Views: 2654

Re: Need a simple circuit for detecting a TTL-level square w

[quote=" Ideally, I would love to use some kind of integrated circuit that is designed to detect square waves/clock signals and produces a "1" when it detects it. But I haven't been able find a chip that would do this. Once I find a solution to this problem, I plan on publishing an article to N&V. I...
by k7elp60
Sat Jan 05, 2008 8:26 pm
Forum: General Discussion
Topic: Judging battery life
Replies: 5
Views: 1858

I have an older data book for Eveready alkaline cells. I looked up the data for a E91(AA). With a constant load of 3mA the battery will last 700 hour to a cutoff voltage of .75 volts or for 3 in series 2.25 volts.
I hope this helps.
Ned
by k7elp60
Tue Jan 01, 2008 5:43 pm
Forum: General Discussion
Topic: 12 volt rechargeable battery
Replies: 5
Views: 2485

There are a couple of places that I know about that will custom make your rechargeable battery. They will spot weld the terminals,encase the pack in heatshrink wrap,supply it with pigtail leads or a connector. They are www.standardsupply.com and www.car-gobattery.com There are even 12V gel-cell batt...
by k7elp60
Sun Dec 09, 2007 4:45 pm
Forum: General Discussion
Topic: patch cord supplier
Replies: 6
Views: 2021

Dave,
Not sure if this will help you, but Caltronics in their on line catalogue has some 2' ones. Here is the link http://www.caltronix.com/
Ned
by k7elp60
Fri Nov 23, 2007 2:30 pm
Forum: Up For Grabs
Topic: LA2730 Dolby B-type noise reduction system
Replies: 3
Views: 3412

LA2730 Dolby B-type noise reduction system

I have 3 ea of these IC's I have no use for. Yours for free.
Ned
P.S. I was unable to find a complete data sheet for them.
by k7elp60
Sun Nov 18, 2007 8:11 am
Forum: General Discussion
Topic: Very small 2mm dc power plug, where to get?
Replies: 4
Views: 1548

Hello Mr. Al, I had a similar problem about a month ago. I normally order from Mouser, so I looked in their catalogue and ordered what I thought was the right one. When it arrived it wasn't the right size. I live in an area where the only place that has electronics parts locallly is Radio Shack. I w...
by k7elp60
Thu Sep 20, 2007 1:05 pm
Forum: General Discussion
Topic: Anyone else here charge/test batteries quite often?
Replies: 12
Views: 3547

Jan Zap "K7elp60 "Lead-Acid have a shelf life of about 6 months after fully charged. This time varies between manufacturers and the temperature at which they are stored. I have found to float them between 2.25 and 2.3 V per cell they will also never over charge. The only ones you have to limit the ...
by k7elp60
Wed Sep 19, 2007 7:09 pm
Forum: General Discussion
Topic: Anyone else here charge/test batteries quite often?
Replies: 12
Views: 3547

Mr Al, I have been doing testing, and building chargers for NiCad NiMH and Lead-Acid batteries for quite a number of years. I wrote a series of articles once for an amateur radio news letter about 8 years ago. I have copies of the complete newsletter in PDF format that I would be glad to share with ...
by k7elp60
Mon Aug 27, 2007 8:17 pm
Forum: General Discussion
Topic: Ion deflection plate switch
Replies: 2
Views: 1219

I can see one possible error in the hand drawn schematic. The VP2450 is a P channel MOSFET. If the 400V terminal is + then the source and the drain of this mosfet need to be reversed.
You also show a 5V battery between pins 5 and 8 of the HCPL4506. Is that a seperate battery or the 5V regulated?
by k7elp60
Tue Jun 19, 2007 6:39 pm
Forum: General Discussion
Topic: Underground electrical signalling ?
Replies: 13
Views: 3452

I once built a device that measured the impedance between two metal poles driven into the earth. This was part of a project to inject audio frequencies into the earth via the two metal stakes. A digital audio generator fed a audio amplifier of about 20 watts. The output of the amplifier was about 8 ...
by k7elp60
Sat Jun 02, 2007 6:20 am
Forum: General Discussion
Topic: crystal radio using vacuum tube diode
Replies: 12
Views: 4274

If memory serves me right, the 6AL5 filament requires 150 ma. A simple task for the right wallwart (6V @ .15 A), The filament voltage dosn't have to be to precise - +/- 10% will do fine. These tubes were used in millions of receivers as AM detectors and FM Foster-Seely discriminators (FM detector)....
by k7elp60
Fri Jun 01, 2007 5:54 pm
Forum: General Discussion
Topic: crystal radio using vacuum tube diode
Replies: 12
Views: 4274

I think it is possible to do the circuit with out a 6.3V transformer. I remember doing something similar a long time a go. What I did was put a regular 120V lamp bulb in series with the vacuum tube filament. It took a long time for the tube to light but it worked. I just did the math and 36 watt bul...
by k7elp60
Wed May 30, 2007 1:49 pm
Forum: General Discussion
Topic: Ferrite antenna on AM receiver...
Replies: 2
Views: 1263

I have two books that have information on ferrite-core antennas, one is the ARRL antenna book and the other one is exploring RF Circuits by Joseph Carr. The both indicate that type of antenna for the am broadcast band is directional in the horizontal position. In the case of the ferrite core antenna...
by k7elp60
Sat May 19, 2007 7:06 pm
Forum: General Discussion
Topic: Obsolete Equipment Manuals
Replies: 4
Views: 1731

Robert here is a list of sites I have. I haven't been to any of them in a while so I don't know how current they are. http://www.tech-systems-labs.com/ http://www.arireggioemilia.org/download/Manuali%20Radio/ http://www.wb4hfn.com/DRAKE/DrakeManuals.htm http://www.hamdirectory.info/icom.html http://...
by k7elp60
Tue Apr 10, 2007 3:26 pm
Forum: General Discussion
Topic: The impending death of incandescent bulbs
Replies: 100
Views: 23269

My two cents worth. I don't like the fluorescent or LEDs lighting, especially as for reading lights. I think they are a poor substitue for the incandescent bulb. I have some solar panels to charge batteries for my amateur radio station equipment. I went one step further and installed some RV light f...