DIYAPASON-L Digest #691 - Saturday, November 23, 2002
 
Re: DIYAPASON-L Digest #690 - 11/21/02
  by "Terry Gibson" <terryg55@nexicom.net>
 

(back) Subject: Re: DIYAPASON-L Digest #690 - 11/21/02 From: "Terry Gibson" <terryg55@nexicom.net> Date: Sat, 23 Nov 2002 14:46:17 -0500   I want to come back into the power suply discussion again since my earlier note regarding adding the 10ohm resistor seems to have opened up lots of discussion. I have some additional thoughts regarding some of the alternatives that = have been put forward. A voltage regulator will do an excellent job, however were = not running CMOS or TTL ICs here, were running chest or action magnets so super smooth regulation may be going overboard a bit depending on cost. The resistor approach will waste some current, but will bring the = operating voltage into the proper range at minimum cost. My general rule of thumb is to use ohms law to select a resistance that will draw up to but not more than 10% of = the total available current. So a 10 amp supply the resistor would be 12v/1.0a =3D 12ohm = resistor, ....a 20 amp supply would require; 12v/2.0a =3D 6 ohm resistor, and so on. Volts times amps gives watts, so minimum rating resistor for 10 amp supply would be 12 X 1 =3D 12watts and = for the 20amp would be 12 X 2 =3D 24 watts. I like to go a little higher on the wattage = because it doesnt seem to get as hot. Make sure the resistor is mounted in a place where heat cant build up, ie = on top of a chasis. As I mentioned in my first note, I have built both 10amp and 20 amp = supplies using this method with great results.   Terry Gibson     ----- Original Message ----- From: "Residence Organ List" <DIYAPASON-L@pipechat.org> To: "Residence Organ List" <DIYAPASON-L@pipechat.org> Sent: Friday, November 22, 2002 12:30 AM Subject: DIYAPASON-L Digest #690 - 11/21/02     > DIYAPASON-L Digest #690 - Thursday, November 21, 2002 > > Re: DIYAPASON-L Digest #689 - 11/20/02 > by <Jess4203@aol.com> > Re: [Residence Organs] Load down discussion > by "John Vanderlee" <jovanderlee@vassar.edu> > Re: [Residence Organs] Re: DIYAPASON-L Digest #687 - 11/18/02 > by "John Vanderlee" <jovanderlee@vassar.edu> > Re: [Residence Organs] Load down discussion > by "Eric Sagmuller" <ess4@psu.edu> > > > ---------------------------------------------------------------------- > > Subject: Re: DIYAPASON-L Digest #689 - 11/20/02 > From: <Jess4203@aol.com> > Date: Thu, 21 Nov 2002 01:42:51 EST > > > --part1_189.113b6838.2b0dda6b_boundary > Content-Type: text/plain; charset=3D"US-ASCII" > Content-Transfer-Encoding: 7bit > > In a message dated 11/21/02 12:30:58 AM Eastern Standard Time, Father = Arp > writes: > > It is > > > far less bugggy than Visual Cadd. > > > Thanks, Father Arp, > > For the very current info and for the beautiffful [computer-type] > figggure of spppeech <BG>. I'd like to hear what something like this would > cost when ready. > > Best Regards & Respectfully, > Roy Kersey > > > > --part1_189.113b6838.2b0dda6b_boundary > Content-Type: text/html; charset=3D"US-ASCII" > Content-Transfer-Encoding: 7bit > > <HTML><FONT FACE=3Darial,helvetica><FONT SIZE=3D2>In a message dated = 11/21/02 12:30:58 AM Eastern Standard Time, Father Arp writes: > <BR><BLOCKQUOTE TYPE=3DCITE style=3D"BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">It is > <BR>&gt; far less bugggy than Visual Cadd. > <BR></FONT><FONT COLOR=3D"#000000" SIZE=3D3 FAMILY=3D"SANSSERIF" = FACE=3D"arial" LANG=3D"0"></BLOCKQUOTE> > <BR></FONT><FONT COLOR=3D"#000000" SIZE=3D2 FAMILY=3D"SANSSERIF" = FACE=3D"Arial" LANG=3D"0">Thanks, Father Arp, > <BR> > <BR> &nbsp;&nbsp;&nbsp;For the very current info and for the beautiffful [computer-type] figggure of spppeech &lt;BG&gt;. &nbsp;I'd like to hear = what something like this would cost when ready. > <BR> > <BR>Best Regards &amp; Respectfully, > <BR>Roy Kersey > <BR> > <BR></FONT></HTML> > > --part1_189.113b6838.2b0dda6b_boundary-- > > ---------------------------------------------------------------------- > > Subject: Re: [Residence Organs] Load down discussion > From: "John Vanderlee" <jovanderlee@vassar.edu> > Date: Thu, 21 Nov 2002 07:58:28 -0800 > > > > >I disagree. Once the resistor is in place, the voltage will be a constant > >12 volts. Simple ohms law tells you that 1.2 amps will flow given 10 ohms. > >This is only 15 watts of heat the resistor will be emitting, a part = rated 20 > >should be fine. > >HOMEPAGE : http://www.diyapason.pipechat.org > >List: mailto:DIYAPASON-L@pipechat.org > >Administration: mailto:owner-DIYAPASON@pipechat.org > > Sorry , I andwered this before I had my morning coffee. Transposed > ohms and amps. > The 1.2 amps is correct and the resistor would be fine. > > Still I would use the IC instead to regulate several branch circuits > and all could be protected by diodes, but the resistor is indeed > simpler although wasteful of current. > > John V...writing out all permutations of Ohm's Law 120 times > > > ---------------------------------------------------------------------- > > Subject: Re: [Residence Organs] Re: DIYAPASON-L Digest #687 - 11/18/02 > From: "John Vanderlee" <jovanderlee@vassar.edu> > Date: Thu, 21 Nov 2002 08:04:43 -0800 > > >> > >> > >>I have been following the power supply discussion, and I wonder if anyone > >>has looked at the ASTRON regulated power supplies? > > > > > >I'm running a 30 amp Astron on my 2/5 Wicks and it does a fine job! > >(Much better than the old Orglectra selenium rectifier that came > >with the beast). I got mine at a hamfest for about $75. Try > >www.aesham.com for good prices. > > > >Dave in Vermont (N1CPP) > > Orgelectras can be salvaged by replacing the selenium rectifier with > a solid state diode bridge of comparable ratings. Your voltage will > go up a bit, but if it has taps you can compensate. or see perevious > discussion on higher voltages. > > John V > > > ---------------------------------------------------------------------- > > Subject: Re: [Residence Organs] Load down discussion > From: "Eric Sagmuller" <ess4@psu.edu> > Date: Thu, 21 Nov 2002 08:20:04 -0500 > > At 04:37 PM 11/20/2002 -0500, you wrote: > >On 11/20/02 11:04 AM, "John Vanderlee" <jovanderlee@vassar.edu> wrote: > > > > >> Steve, > > >> There is a simple solution to your problem. I have built many power > > supplies > > >> including > > >> the one I use on my own organ. Whats happening is the capacitor is > > charging > > >> to the > > >> peak voltage it sees when there is no load on it. A 12 volt supply means > > >> 12volts RMS, > > >> however the peak voltage is actually a little over 16 volts. > > >> The solution is to add a wirewound resistor across the capacitor, I > > suggest > > >> approx 10ohms > > >> and rated at about 20watts. This should drop your peak voltage back > > into the > > >> 12-13 volt range. > > I just recently built a beefy, unregulated, 30+ amp supply to run my > Peterson combination action. This supply was running about 17 volts. Adding > a 20 ohm resistor across the output only dropped the peak voltage down = to > 16 volts. When the action was operated the voltage only dropped to about 14 > volts with approx. 20 amps being drawn. If the supply drops from 16 = volts > to 12 volts with only 1.2 amps being drawn then it is a very spongy supply. > This is speaking of a capacitor input supply. Some that use chokes may > react differently. My stoptabs were running too hard so I added a small > buck transformer to get the voltage down to about 13 volts unloaded. Of > course I have two large mfd. capacitors in the supply which initially keeps > the voltage from dropping in the first instant that the tabs move. > > I plan to obtain an Astron supply when I switch my organ to all > electro-mechanical action. As some have stated I think they're the best > deal. A combination action only draws a pulse of power, so a capacitor > input supply is plenty, and much cheaper, at least for me as I could = build it. > > > > ---------------------------------------------------------------------- > End of DIYAPASON-L Digest > > DIYAPASON-L: a Discussion list for owners and builders of their own Residence Pipe Organs. > HOMEPAGE : http://www.diyapason.pipechat.org > List: mailto:DIYAPASON-L@pipechat.org > Administration: mailto:owner-DIYAPASON@pipechat.org >