Search found 36 matches

by ki3u
Sun Dec 31, 2017 5:38 pm
Forum: General Discussion
Topic: Santa Claus Christmas Music Box repair
Replies: 0
Views: 59072

Santa Claus Christmas Music Box repair

Judging from online reviews a significant fraction of the polyresin-based Christmas-theme Music Boxes coming out of China have problems brand-new out of the box, right up to totally disfunctional. I thought it worthwhile to devote a little webpage on my website to the diagnosis and repair of a parti...
by ki3u
Sat Dec 16, 2017 10:37 am
Forum: General Discussion
Topic: Experimental analog-circuit gas detector / alarm
Replies: 2
Views: 33647

Re: Experimental analog-circuit gas detector / alarm

NeilXu wrote : " Hi...i am a new user here. I took a look at your circuit and there a few things that I can mention. Firstly, if you need something as complex as a GSM Modem, you will need to create a LabVIEW instrument for it if that is possible. If you know the exact input you are going to re...
by ki3u
Mon Oct 30, 2017 3:58 pm
Forum: General Discussion
Topic: Experimental analog-circuit gas detector / alarm
Replies: 2
Views: 33647

Experimental analog-circuit gas detector / alarm

For anyone interested I've put online on my website a description of my experiments resulting in the development of an experimental gas detector / alarm based on analog circuitry, and not involving any digital electronics : http://ki3u.byethost3.com/Instruments_etc/Exp_Gas_Detector/Exp_gas-detector-...
by ki3u
Mon Jun 26, 2017 5:52 pm
Forum: General Discussion
Topic: Cooling troubling electronics
Replies: 0
Views: 58989

Cooling troubling electronics

Sometimes often enough you can get lucky and implement a quick and easy fix, if only a temporary one, of
a troubling electronic device :

http://ki3u.byethost3.com/Radio-Physics ... onics.html

Berj / KI3U
by ki3u
Tue May 02, 2017 9:34 am
Forum: General Discussion
Topic: Raising the frequency of a quartz crystal
Replies: 2
Views: 20394

Re: Raising the frequency of a quartz crystal

Hi Jeff r tnx. Well it's a useful skill to change these older crystals for modern use - there are still tons of them available. Lets note that the FT 243 types were intended for vacuum tube circuits, but as we see in the article the crystal oscillates nicely in a one-transistor test oscillator power...
by ki3u
Sat Apr 29, 2017 3:48 pm
Forum: General Discussion
Topic: Raising the frequency of a quartz crystal
Replies: 2
Views: 20394

Raising the frequency of a quartz crystal

For those interested I have some data on raising the oscillation frequency of quartz crystals, in particular moving a
5675 KHz crystal up to 6109 KHz :

http://ki3u.byethost3.com/Radio-Physics ... uency.html

Berj / KI3U
by ki3u
Sat Aug 27, 2016 9:14 am
Forum: General Discussion
Topic: Very simple, very effective outboard CW Audio Filter
Replies: 0
Views: 55644

Very simple, very effective outboard CW Audio Filter

It is possible to realize an excellent CW radiotelegraph outboard passive audio filter with just one inductor and one capacitor. I describe this in some detail on this page of my website : http://ki3u.byethost3.com/Radio-PhysicsDIR/ecomDIR/Simple_passive_CW-filter/Simple%20passive%20CW%20audio%20fil...
by ki3u
Tue May 03, 2016 3:44 am
Forum: General Discussion
Topic: Reversing the Midland 23-136 SWR Meter's ports
Replies: 0
Views: 30347

Reversing the Midland 23-136 SWR Meter's ports

If convenience in the radio station calls for it, it couldn't be simpler to reverse the port directions of the Midland 23-136 SWR and Power Meter (and similar units of this rebrand instrument) : http://ki3u.byethost3.com/Radio-PhysicsDIR/Radio_Equipment/Midland%2023-136%20SWR%20Meter/Reversing%20the...
by ki3u
Wed Aug 19, 2015 7:32 pm
Forum: General Discussion
Topic: Amplified Computer Speakers converted to Intercom
Replies: 0
Views: 23600

Amplified Computer Speakers converted to Intercom

I've converted an old MLI 691 PA amplified computer speakers system to a wired intercom :

http://ki3u.byethost3.com/Radio-Physics ... ercom.html

The conversion is very simple and works really well.

Berj / KI3U
by ki3u
Sun Nov 09, 2014 10:35 pm
Forum: General Discussion
Topic: Acoustic Coupler for Amateur Radio Digital Modes
Replies: 0
Views: 19091

Acoustic Coupler for Amateur Radio Digital Modes

For amateur radio digital modes I built an acoustic coupler interface between the transceiver and computer to eliminate computer problems on key down. It's worked well so far. A friend of mine suggested I describe it online, so I've just put it up on my website if anyone's interested: http://ki3u.by...