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 Post subject: Zenith 3000-1 AC Adapter
PostPosted: Jun Wed 12, 2019 3:01 pm 
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Joined: Mar Sun 24, 2019 12:08 am
Posts: 4
Does anyone have experience with the AC adapter on eBay. Says regulated 12V with something called ICL. Looks good and has all positive feedback. $24 shipped but takes offers.. :roll:


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 Post subject: Re: Zenith 3000-1 AC Adapter
PostPosted: Jun Wed 12, 2019 5:05 pm 
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Joined: Aug Wed 24, 2011 4:35 am
Posts: 4528
Location: Sunnyvale CA
1R5X50 wrote:
Does anyone have experience with the AC adapter on eBay. Says regulated 12V with something called ICL. Looks good and has all positive feedback. $24 shipped but takes offers.. :roll:



I have no specific information about this adapter but the general requirements for the power supply are extremely undemanding, only about 20-25 mA at 11-12.5V. Almost anything with a regulated 12V output would work if you get the polarity on the plug the right way around. I think I got mine for about $1.75 from at Halted electronics, they had a huge box of them. I cut the wire, flipped the polarity around, and spliced it back, works fine.

Many unregulated "12V" wall-warts will float to higher voltages when presented with the very low current draw of the radio, since they depend on the load depressing the voltage, so maybe a 9V 100 mA wall war will float up to 12V under 20 mA. I don't see any good way of telling how that will work for any particular supply. I would just get a regulated type, they are cheap - much cheaper than $24!

The polarity is critical, however. It's opposite from almost any modern adaptor, the center pin is NEGATIVE and the ring/shield is POSITIVE.

By the way, I have both an original Zenith wall-wart (that looks like something rejected by the Russian Army) and the cheapie I mentioned. I almost never use them, 8 D alkaline batteries last an eternity.

Brett


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 Post subject: Re: Zenith 3000-1 AC Adapter
PostPosted: Jun Wed 12, 2019 9:03 pm 
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Joined: Jan Tue 31, 2012 1:55 am
Posts: 9853
Location: Mountains of Mourne. Ireland.
Just use batteries, they will last for years.
viewtopic.php?f=4&t=349144

Greg.


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 Post subject: Re: Zenith 3000-1 AC Adapter
PostPosted: Jun Thu 13, 2019 1:26 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 6506
Location: Black Hills, SD 57745
Just measure the prospective wallwart's unloaded voltage with your DMM. As noted, most cheapy 9v types will run around 12v unloaded, so they would work fine. The deal is, the Zenith's Germanium transistors don't cotton to getting much over 12v. What with the radio's legendary miserly battery-draw, it's all too easy to overvolt it. That's the primary power supply issue.

So far as powering off batteries, I just stubbed in a 9v connector and use a lightweight 9v Alkaline. The 3000 works just as well with those and is much lighter/cheaper than installing 8 D-cells. Besides, when going mobile with it, it saves the weight stress to the flimsy Antenna/handle! If it's your daily driver for several hours per day, then it would make sense to pop for the bulkier D-cells or go 9v wallwart.

-Ed

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 Post subject: Re: Zenith 3000-1 AC Adapter
PostPosted: Jun Thu 13, 2019 1:09 pm 
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Joined: Mar Sun 24, 2019 12:08 am
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Ed in SoDak wrote:
Just measure the prospective wallwart's unloaded voltage with your DMM. As noted, most cheapy 9v types will run around 12v unloaded, so they would work fine.
-Ed

Thanks for the info and I hear ya. I've noticed no load voltage on old school transformer type 9V wallwarts ranges from about 13.5 to around 15V. A small load brings it down to around 12 and ofcourse rated load to around 9. I actually use old 9V blocks as float chargers on a couple seasonal cars I own. Works fine..as battery voltage drops wallwart current inherently increases maintaining 12.5-13V...not sure I want all this variability for my poor old transistor TO but I appreciate the insights..


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 Post subject: Re: Zenith 3000-1 AC Adapter
PostPosted: Jun Fri 14, 2019 5:25 am 
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Joined: Aug Wed 24, 2011 4:35 am
Posts: 4528
Location: Sunnyvale CA
1R5X50 wrote:
Ed in SoDak wrote:
Just measure the prospective wallwart's unloaded voltage with your DMM. As noted, most cheapy 9v types will run around 12v unloaded, so they would work fine.
-Ed

Thanks for the info and I hear ya. I've noticed no load voltage on old school transformer type 9V wallwarts ranges from about 13.5 to around 15V. A small load brings it down to around 12 and ofcourse rated load to around 9. I actually use old 9V blocks as float chargers on a couple seasonal cars I own. Works fine..as battery voltage drops wallwart current inherently increases maintaining 12.5-13V...not sure I want all this variability for my poor old transistor TO but I appreciate the insights..



https://www.amazon.com/lm7812-voltage-r ... +regulator - ~40 cents.

Brett


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 Post subject: Re: Zenith 3000-1 AC Adapter
PostPosted: Jun Fri 14, 2019 1:22 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 781
Location: dayton oh usa
dont forget the caps from g to in and g to out.
i usually use 10uf 25v tantalums.
without these it may oscillate!


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