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MM
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Post subject: hp 204b generator  Posted: Nov Fri 15, 2019 9:03 am |
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Joined: Nov Wed 15, 2006 7:56 am
Posts: 1421
Location: germany
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I found in the bay a 204b for 10,5e this is the next restoration 
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bob91343
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Post subject: Re: hp 204b generator Posted: Nov Fri 15, 2019 6:09 pm |
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Joined: Jan Tue 10, 2012 8:39 am
Posts: 1965
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I have an HP 201B that is looking and working well. Now what? I don't have room for a museum.
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stevebyan
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Post subject: Re: hp 204b generator Posted: Nov Fri 15, 2019 8:07 pm |
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Joined: May Wed 18, 2011 2:40 am
Posts: 5168
Location: Littleton, MA
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The 204B is unique as it is the only version of the 204 that it tunes the frequency by varying the resistance rather than the capacitance in the Wien bridge.
The 204A is a version of the 200, capacitance tuned, using battery tubes, with dry cell battery power.
The 204B is the first transistor version, resistance tuned, again with mercury battery power. AC only power is option 01, rechargeable NiCd battery power is option 02.
The 204C is a transistor version that is capacitance tuned, as is the 204D.
I have a 204B sitting in the restoration queue, I'll be interested in what you encounter when you restore yours.
_________________
Steve Byan https://www.byan-roper.org/steve/steve-at-play/
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bob91343
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Post subject: Re: hp 204b generator Posted: Nov Fri 15, 2019 11:22 pm |
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Joined: Jan Tue 10, 2012 8:39 am
Posts: 1965
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Most of the pleasure is in the restoration. Using the gear afterwards isn't that big a deal.
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MM
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Post subject: Re: hp 204b generator Posted: Nov Wed 27, 2019 9:42 pm |
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Joined: Nov Wed 15, 2006 7:56 am
Posts: 1421
Location: germany
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.. but how to find this batteries?  6.75V mercury TR235, 4pcs. Attachment:
204.jpg [ 168.16 KiB | Viewed 899 times ]
Attachment:
204-4a.jpg [ 337.3 KiB | Viewed 899 times ]
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MM
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Post subject: Re: hp 204b generator Posted: Dec Sun 29, 2019 4:15 pm |
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Joined: Nov Wed 15, 2006 7:56 am
Posts: 1421
Location: germany
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homebrew AC Option for 204B Attachment:
204-1a.jpg [ 217.37 KiB | Viewed 764 times ]
T1 was defect, 2N1516. Attachment:
204-6a.jpg [ 185.58 KiB | Viewed 764 times ]
replaced with a AF118 Attachment:
204-8a.jpg [ 276.8 KiB | Viewed 764 times ]
it works  Attachment:
204-7a.jpg [ 286.43 KiB | Viewed 764 times ]
done. Attachment:
204-9a.jpg [ 281.35 KiB | Viewed 764 times ]
Martin
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stevebyan
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Post subject: Re: hp 204b generator Posted: Dec Sun 29, 2019 5:05 pm |
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Joined: May Wed 18, 2011 2:40 am
Posts: 5168
Location: Littleton, MA
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MM
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Post subject: Re: hp 204b generator Posted: Dec Sun 29, 2019 5:17 pm |
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Joined: Nov Wed 15, 2006 7:56 am
Posts: 1421
Location: germany
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AC Option:
The required voltage of 13,5V is by using a 78L08, in series with the ground pin a zener 5,6V.
This is to build 2x to get the ±13,5V.
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