Subject: From: Date:

Re: [ECS] micro-redac and relays Dan Carrington Mon, 04 Jan 1999 17:22:13 -0800

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No.  The diode is to to backwards across the coil to short induced
spikes when the coil lets go of the relay.  It would not do anything if
across the switch side, unless you put it in the wrong way at which
point it would completely short the power supply.  My concern when I
posted the info, is that I wonder how you use multiple digital inputs if
you are feeding them with different wall warts (power transformers). 
Are you commoning them into the common side of the digital inputs?  If
so, that could be dangerous!!!  For safety, you should use one common
power supply for all inputs and just switch it into the inputs, which
solves the problem of delay with capacitor equipped wall warts.

Dan Carrington




Mark Sekelsky wrote:
> 
> David & Dan,
> 
> Sorry to take so long to get back regarding your continued suggestions on my
> Redac and receiver.  Spent the weekend shoveling out from all the snow and
> had no phone service at all on Sunday (:  A couple more questions (I don't
> promise that they are the last <g>) if I may.  Both of the most recent
> suggestions are a little over my head, although I am sure I could eventually
> figure it out.  So question number one is:
> 
> What if I just leave everything the way it is?  While not excited about the
> 9" delay in changing the state to HIGH it is not a big deal.  The big reason
> that I want to check power is that neither the IR Master nor a HV that I
> played with have been able to control my receiver 100%.  My event already
> incorporates a delay on and off timer so that I can resend the signal if the
> state of the receiver isn't changed.  I was using a 6" delay to test for OFF
> but all I have done now is increase it to 12."  Even if my response time is
> instantaneous I will incorporate some type of delay check.
> 
> Question number two.  Could I take the diode that Dan recommends and attach
> that to the Redac in my existing system?
> 
> Mark S
> 
> -----Original Message-----
> From: David Mccoll [mailto:dmccoll@intergate.bc.ca]
> Sent: Friday, January 01, 1999 8:36 PM
> To: ecs-list@netbloc.com
> Subject: Re: [ECS] micro-redac and relays
> 
> Mark S,
> The transition should be spontaneous with no delay at all. You have a good
> point about the residuals in the power-pak. There must be a capacitor inside
> the power-pak. You can bleed the stored energy off with a resistor connected
> across the two leads before the digital input of Redac. I suggest placing
> the resistor before the fuse and resistor for the input.
> 
> Start with a 2.2kOhm  and move down until you get it working well. Check how
> hot the resistor gets with the receiver on. When the receiver is on, the
> added resistor will dissipate the energy and get hot. This is ok but if it
> gets too hot it can be a hazard. If the resistors are 1/2 Watt then they can
> dissipate 1/2 Watt max. A 1/8 Watt resistors will be a little small for the
> job. You can halve the heat through the resistor by using 2 resistors in
> parallel but you MUST double the value of both resistors when you parallel
> them. This shares the load between them. When you are finished you may want
> to spring a couple dollars for a 5 Watt ceramic resistor.
> 
> I figure a good value would be 500Ohm across 12Volt = .024Amp and .28Watt.
> A 1 Watt will do, and a 5 Watt is more than adequate.  If you want to use
> other values you can use the Ohm's Law calculator at this url:
> 
> http://webhome.idirect.com/~jadams/electronics/ohms_calc.htm
> 
> DAvid M
> 
> -----Original Message-----
> From: Mark Sekelsky <Mark@sekelsky.com>
> To: ecs-list@netbloc.com <ecs-list@netbloc.com>
> Date: Thursday, December 31, 1998 4:16 PM
> Subject: RE: [ECS] micro-redac and relays
> 
> >David,
> >
> >Thanks for the resistor lesson.  The 2.2 didn't work but the 1K sort of
> >does.  With only a fuse in place there is about a 3-4" delay before the
> item
> >state changes to HIGH.  I assume this is residual power in the transformer.
> >With the 1K resistor in place that delay is 8-9" but it does change to HIGH
> >100% of the time.  I can certainly live with this but wonder if it means I
> >should be trying yet another resistor or not.
> >
> >Happy New Year!
> >
> >Mark S
> >
> >-----Original Message-----
> >From: David Mccoll [mailto:dmccoll@intergate.bc.ca]
> >Sent: Wednesday, December 30, 1998 4:13 PM
> >To: ecs-list@netbloc.com
> >Subject: Re: [ECS] micro-redac and relays
> >
> >
> >Mark S
> >Your connections sound correct. Get it to work 100% before you add the fuse
> >and resistor. If the 10K resistor gives you trouble move down to a 4700
> that
> >is a Yellow, Violet, Red, Gold. If that does not work then move down to a
> >2.2K or 2200 which would be Red, Red, Red, Gold. If that does not work then
> >go to a 1K or 1000 which is Brown, Black, Red, Gold.
> >
> >Originally you said the power pak was 5V DC 150mA. What are you using now ?
> >
> >Here is some gunk on resistors. This is very simple stuff but on the
> surface
> >it may look complicated. The Gold band is what is referred to as the
> >"tolerance" of the resistor and is usually the last band.
> >
> >Gold is 5% -- most common tolerance
> >Silver is 10% -- not too common
> >
> >The first 3 bands are the value.  Here is the way I learned to calculate
> it.
> >Bad  ---  Black -- 0  -- .0
> >Boys  --- Brown -- 1 -- 0
> >Rape --- Red -- 2 -- 00
> >Our  --- Orange -- 3 -- 000
> >Young --- Yellow -- 4 -- 0000
> >Girls --- Green -- 5 -- 00000
> >But  --- Blue -- 6 -- 000000
> >Violet ---- Violet -- 7 --0000000
> >Goes --- Gray -- 8 -- 00000000
> >Without  -- White -- 9 -- 000000000
> >
> >The first 2 bands are the value and the third band is the multiplier which
> >is the number of 0's to add after the value. So 4.7 K.Ohms = 4700 Ohms =
> >Yellow, Violet, Red and Gold for the 5% tolerance. The 10KOhm resistor
> would
> >be Brown, Black and Orange the multiplier is usually assumed to be 5% Gold.
> >A 100 Ohm resistor is Brown Black Brown and a 10 Ohm is Brown,Black, Black
> >
> >Keep up the good work.
> >
> >DAvid M
> >
> >
> >
> >

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