I need an IDIOTS guide to making as AC adapter for a Zenith Z-28 battery pack. And please I do mean an idiots guide. Thanks, Brett

:I need an IDIOTS guide to making as AC adapter for a Zenith Z-28 battery pack. And please I do mean an idiots guide. Thanks, Brett

Check here..

http://www.antiqueradio.org/tobatt.htm

Some Radio Shacks still carry a small aluminum chassis, which is perfect for making a small power supply--if you choose to work with tubes. They also carry just about everything you need except for 30-40 MFD 200 WVDC electrolytics. If you use the metal chassis, it is also nice to mount a multi-section electrolytic on top, if you can find one that suits your needs. If you want the supply to be more compact, you should probably avoid things like an external electrolytic and a tube.

While I choose to go the traditional route in feeding everything from a 117Z6GT tube, this requires a large dropping resistor (at least 1800 ohms at about 50 watts) for the filaments, and also requires rewiring 1.5 volt sets in series, which also requires relocating biasing points within the set, as well as adding small electrolytics to the filament string. You cannot practically feed a set where the tube filaments are wired in parallel by using the tube and dropping resistor method. The current draw will be too high.

A better set-up allows you to adjust for either 1.5 volt sets or higher voltage sets (6 volt, 7.5 volt, 9 volt, etc.), and requires no re-wiring of the actual radio. Purchase an LM317 voltage regulator and the required parts listed on the package. Purchase the smallest power transformer that Radio Shack sells (6-0-6 volt AC). This should be adequate for most battery portables. Purchase a small full wave rectifier capable of handling 1 ampere (nothing more is necessary). Purchase some 1000 MFD 35 WVDC electrolytics. Wire up the rectifier across the 12 volt AC source (wire across a 6 volt section if you don't intend to obtain more than 6 volts...this will make the regulator run cooler). Connect a 1000 MFD cap on the DC side of the rectifier. Wire up your regulator. Connect a 1000 MFD cap on the output of the regulator. Adjust the voltage to your preference.

For the B section of the power supply, you can either purchase a full wave rectifier from Radio Shack capable of line voltages. I believe that theirs is rated for 400 volts. It doesn't need to handle more than 1 ampere. ....Or you can wire up a half wave rectifier using the 117Z6GT tube, which gives the power supply a nice look. Use a couple of 47 MFD 250 WVDC caps in the supply. Place a 100 ohm resistor on the positive output of the rectifier (cathode of the 117Z6 or positive terminal of the solid state rectifier). Place a 47 MFD 250 WVDC cap from the resistor to the negative side of the power supply. Place a suitable dropping resistor after the 100 ohm resistor to obtain your final voltage, and then place another 47 MFD cap after that for final filtering. My Zenith 5-G-500 uses a 2700 ohm resistor to feed the radio 90 volts B+. Use more or less resistance to suit your radio. Current draw in these radios is low, so you might get away with a nice sized potentiometer.

If you wish to have line isolation, purchase another one of those 6-0-6 volt transformers and connect the secondary of this transformer to the secondary of the transformer previously mentioned. Use the primary of this transformer to feed the B supply rectifier.
T.

:Some Radio Shacks still carry a small aluminum chassis, which is perfect for making a small power supply--if you choose to work with tubes. They also carry just about everything you need except for 30-40 MFD 200 WVDC electrolytics. If you use the metal chassis, it is also nice to mount a multi-section electrolytic on top, if you can find one that suits your needs. If you want the supply to be more compact, you should probably avoid things like an external electrolytic and a tube.
:
:While I choose to go the traditional route in feeding everything from a 117Z6GT tube, this requires a large dropping resistor (at least 1800 ohms at about 50 watts) for the filaments, and also requires rewiring 1.5 volt sets in series, which also requires relocating biasing points within the set, as well as adding small electrolytics to the filament string. You cannot practically feed a set where the tube filaments are wired in parallel by using the tube and dropping resistor method. The current draw will be too high.
:
:A better set-up allows you to adjust for either 1.5 volt sets or higher voltage sets (6 volt, 7.5 volt, 9 volt, etc.), and requires no re-wiring of the actual radio. Purchase an LM317 voltage regulator and the required parts listed on the package. Purchase the smallest power transformer that Radio Shack sells (6-0-6 volt AC). This should be adequate for most battery portables. Purchase a small full wave rectifier capable of handling 1 ampere (nothing more is necessary). Purchase some 1000 MFD 35 WVDC electrolytics. Wire up the rectifier across the 12 volt AC source (wire across a 6 volt section if you don't intend to obtain more than 6 volts...this will make the regulator run cooler). Connect a 1000 MFD cap on the DC side of the rectifier. Wire up your regulator. Connect a 1000 MFD cap on the output of the regulator. Adjust the voltage to your preference.
:
:For the B section of the power supply, you can either purchase a full wave rectifier from Radio Shack capable of line voltages. I believe that theirs is rated for 400 volts. It doesn't need to handle more than 1 ampere. ....Or you can wire up a half wave rectifier using the 117Z6GT tube, which gives the power supply a nice look. Use a couple of 47 MFD 250 WVDC caps in the supply. Place a 100 ohm resistor on the positive output of the rectifier (cathode of the 117Z6 or positive terminal of the solid state rectifier). Place a 47 MFD 250 WVDC cap from the resistor to the negative side of the power supply. Place a suitable dropping resistor after the 100 ohm resistor to obtain your final voltage, and then place another 47 MFD cap after that for final filtering. My Zenith 5-G-500 uses a 2700 ohm resistor to feed the radio 90 volts B+. Use more or less resistance to suit your radio. Current draw in these radios is low, so you might get away with a nice sized potentiometer.
:
:If you wish to have line isolation, purchase another one of those 6-0-6 volt transformers and connect the secondary of this transformer to the secondary of the transformer previously mentioned. Use the primary of this transformer to feed the B supply rectifier.
:T.