For Darren

[StirCrazy]

hey will a diod act as a check valve alowing cureent to flow one way but not the other?
I was thinking about putting abit of insurance that one balast won't try feed the other with my lighting arangment.

Steve

[titus]

Hello Steve,

Yes diodes are check valves for electricity. More or less.

[DJ88]

More or less they are a check valve. Thing is you will need to get something made to handle high currnet and voltage. Most diodes won't. You will overcome it's resistance to the flow of electrons then poof. Factory Installed smoke..

Ensure you have one capable of handling the voltages and currents you are expecting plus a generous amount over and above that for spikes of current etc.

How do you plan on wiring it in?

[Silverfish]

Hope I didn't get you thinking too hard on that one Steve!! images/smiles/icon_biggrin.gif

Darren, the question was regarding a thread on RC (Victor's recent thread on overdriving florecent) Steve said he wanted to overdrive three 36" NO 03 actinics with two electronic magnatek ballasts designed for running three lamps. He wants to use the two ballasts as a dimmer/brightener, as in having one ballast come on, then later have the other ballast come on. I like the idea, but threw in the question of voltage back feeding to the ballast that is not yet fired.

just wanted to get other peoples gears turning!! images/smiles/icon_wink.gif

[StirCrazy]

Ok Darren here is how I want to wire it.

http://members.shaw.ca/stircrazy/wiring.jpg

as you can see I would like to put diodes on each wire comming out of the balast to protect the balast against back feed.. or is this nessasary? I am using a 2 bulb balast for the example.

Steve

[DJ88]

You will want diodes or some form of protection from current going back into the unpowered ballast.

[StirCrazy]

ok now next question for our resadent electronic specialists images/smiles/icon_biggrin.gif
what kinda diode would allow up to 1 amp/120v in one direction and stop it in the other..? I was looking on radioshack's page but there are to many types of diodes.
(basicly I want to allow 40watts to pass through but nothing to be able to come back so the shut down balast will not be fed by the running one. I will put a diode on each wire also so I think a 1 amp sustained stopping capability should be enuf)

how can you tell I am getting close to the time to put everything togeather.. got too work out all the little stuff that has been put off due to procastanation images/smiles/icon_rolleyes.gif

hmm to bad I can't remember most of the electronic stuff I was taught images/smiles/icon_wink.gif

Steve

[ 08 January 2002: Message edited by: StirCrazy ]

[DJ88]

Looking for one now for you.. Or trying at least..

What you want to tell the guy at the distributor is this.


<UL TYPE=SQUARE><LI>VRRM (Peak Repetative Reverse Voltage) over 150V. Voltage Diode will stop in reverse. After this it self destructs.

<LI>IRRM (Peak Repetative Reverse Current) over 2A. This is where it will self destruct if too much current is sent through backwards.

<LI>IFACM (Forward Average Current Max) I'd go 2amps. Gives you breathing space. More if you want. Or less if you want to cut it close. Max current it can handle when forward biased(turned on and letting electrons flow)

<LI>IFSM Forward Surge Curent Max. About 3 to 5 Amps. Deepnds on what you can get. Basically the point at which the Diode "blows" up with surges. Higher than Average current. Since the lamps can handle it you really dont need to set it exact. Go high.. images/smiles/icon_wink.gif

<LI>Vf Forward Voltage Drop. Voltage required to "turn" the Diode ON. Or let electrons flow. As low as possible. Say 1V. Once the Diode is biased this is not a concern.

[/list]

These are numbers off of the top of my head.. Make sure the Diode can handle what you are putting into it. Forward and reverse.

Find a local electronics supplier adn tell them waht it is for. If I had some parts books handy I'd give you the numbers for exactly what you want.

Just remember.. BE SAFE!! Anything above .5A can really mess you up.... You are dealing with 1A or more here..

[ 08 January 2002: Message edited by: DJ88 ]

[ 08 January 2002: Message edited by: DJ88 ]

[reefburnaby]

Hi,

Sorry for the delay...I was busy today -- Jury Duty. Anyway, I don't think diodes will help you in this situation because the ballasts are actually driving AC signals, so there will be a negative and positive signal component. If you place a diode in series, it will block one of the components (hence, half as bright). The AC signals is operating around 10 to 100 kHz (hence electronic switching ballast). But...you can try it...you'll need a 1n4007....1kV/1A forwad bias diode. A more common 1n4005 may work too (600V/1A) Fairly generic diodes....

Your best bet is to put in a relay between the bulbs and the ballast (plus the power). Personally, I think you should be okay without any protection. There is already built in protection within the device that prevents the switcher transistors from blowing up.

- Victor.

[StirCrazy]

hmmm ok I never knew there was built in protection. ok now for the stupid question.. how does a relay work that will make it benificial?

Steve

[DJ88]

Aww crap didn't even clue in.. grrr.. freaking finals.. grrr.. @#@*^$(#^%@

[reefburnaby]

Hi,

A relay electrically isolates, by physical means, the ballast outputs from the tube (and the other ballast). Think of a relay has an electrical switch that can be controlled electrically.

There is built in protection in side the ballast because they usually use HEXFET transistors as the main driver. They are very sensitive to voltage over-stress. Hence, they do have built in diode to prevent voltage over-stress from damaging the transistor. Voltage overstress can occur when there is feedback (aka refelections) from the load (lamps).

- Victor.

[StirCrazy]

hmmok I think I know what you meean.. I could set a relay up so that when it sences power on the plug side of the balast it will close and let power out to the ballast. when my timer shut off it would sence no power and open the relay.. damn Not bad for a stoker eh Darrren images/smiles/icon_biggrin.gif

Steve

[StirCrazy]

ok I went to quale and the bigest AC relay I could find was a 4 pole. so relay and socket comes to 20.00 and I need to isolate 6 wires at least.. I would have love to find two 6 or 8 pole relays but I couldent. so I think I am going to try it with out the relays.. if the ballasts have protection I am fine.. if they don't I smoke a 45.00 ballast and when I buy a new one I will fork out the 40.00 for relays also images/smiles/icon_biggrin.gif

Steve

[reefburnaby]

Hi,

I think radioshack sells them cheaper. I think they were $10....you don't need tons of current. 1A max.

[StirCrazy]

ok if I hook up the two ballasts and run them and one blows up images/smiles/icon_smile.gif would the wholsaler be able to tell it blew up because I hooked it up in a unrecomended mannor images/smiles/icon_biggrin.gif images/smiles/icon_biggrin.gif
or would I get aways with.. I don't know what happened, I turned on the lights and.... images/smiles/icon_wink.gif

Steve

[ 24 January 2002: Message edited by: StirCrazy ]</p>