Valve preamp

D

Dave.H

Guest
I have found a valve preamp kit in an online store, to go between an
amplifier based on an LM380 chip, and a crystal or regen radio, but it
uses a microphone where I want an audio input. If anyone can tell me
how to connect an audio in one this or give me a schematic for a low
voltage preamp using a single 12AU7 tube, I'd be grateful


Thanks
Dave
 
"Dave.H" wrote:

I have found a valve preamp kit in an online store, to go between an
amplifier based on an LM380 chip, and a crystal or regen radio
Click to expand...
Forget. It's designed for nuts who like to add a special type of
distortion to their hi-fis'

For God's Sake buy the National Semiconductor Audio handbook (I think it's
back in print now) and/or the TI Bifet manual. Or download them.

And /or also 'op-amps for everyone' (IIRC) from TI.

http://www.amazon.com/National-Semiconductor-Audio-Radio-Handbook/dp/1882580354/ref=sr_1_2?ie=UTF8&s=books&qid=1213802822&sr=8-2

http://focus.ti.com/lit/an/slod006b/slod006b.pdf
http://focus.ti.com/lit/an/sboa092a/sboa092a.pdf
http://www.amazon.com/Op-Amps-Everyone-Ron-Mancini/dp/0750677015

And stop looking at crackpot sites using 30 year old chips ffs.

Graham
 
"Dave.H" wrote:

"Dave.H" <the19...@googlemail.com> wrote:
I have found a valve preamp kit in an online store, to go between an
amplifier based on an LM380 chip, and a crystal or regen radio, but it
uses a microphone where I want an audio input. If anyone can tell me
how to connect an audio in one this or give me a schematic for a low
voltage preamp using a single 12AU7 tube, I'd be grateful


Oops, forgot the link to the preamp kit,
http://secure.oatleyelectronics.com//product_info.php?products_id=722

They do have (had) another similar preamp with an audio input, but
none are in stock now (discontinued)
Click to expand...
Fascinating in its own way but utterly irrelevant to what you require.

Stop looking for 'kits' and do some *learning*. Then you can design your own
kits. Less than one day's appropriate study should do it.


Graham
 
On Jun 19, 12:23 am, "Dave.H" <the19...@googlemail.com> wrote:
I have found a valve preamp kit in an online store, to go between an
amplifier based on an LM380 chip, and a crystal or regen radio, but it
uses a microphone where I want an audio input. If anyone can tell me
how to connect an audio in one this or give me a schematic for a low
voltage preamp using a single 12AU7 tube, I'd be grateful

Thanks
Dave
Click to expand...
Oops, forgot the link to the preamp kit,
http://secure.oatleyelectronics.com//product_info.php?products_id=722

They do have (had) another similar preamp with an audio input, but
none are in stock now (discontinued)
 
On Jun 19, 1:46 am, "ian field" <dai....@ntlworld.com> wrote:
"Dave.H" <the19...@googlemail.com> wrote in message

news:5a943c3d-af76-42d7-8745-2dfc65a2bc3c@a9g2000prl.googlegroups.com...

On Jun 19, 12:23 am, "Dave.H" <the19...@googlemail.com> wrote:
I have found a valve preamp kit in an online store, to go between an
amplifier based on an LM380 chip, and a crystal or regen radio, but it
uses a microphone where I want an audio input. If anyone can tell me
how to connect an audio in one this or give me a schematic for a low
voltage preamp using a single 12AU7 tube, I'd be grateful

Thanks
Dave

Oops, forgot the link to the preamp kit,
http://secure.oatleyelectronics.com//product_info.php?products_id=722

They do have (had) another similar preamp with an audio input, but
none are in stock now (discontinued)

Can you upload the regen schematic to a picture host and post the link?
Click to expand...
http://www.oldradios.co.nz/hikers/, it's the 1951 Improved Hiker's one
valve
 
On Jun 20, 12:42 am, "ian field" <dai....@ntlworld.com> wrote:
"Dave.H" <the19...@googlemail.com> wrote in message

news:404015e4-00e7-40f0-badc-1a5beb73ba39@h1g2000prh.googlegroups.com...



On Jun 19, 1:46 am, "ian field" <dai....@ntlworld.com> wrote:
"Dave.H" <the19...@googlemail.com> wrote in message

news:5a943c3d-af76-42d7-8745-2dfc65a2bc3c@a9g2000prl.googlegroups.com...

On Jun 19, 12:23 am, "Dave.H" <the19...@googlemail.com> wrote:
I have found a valve preamp kit in an online store, to go between an
amplifier based on an LM380 chip, and a crystal or regen radio, but it
uses a microphone where I want an audio input. If anyone can tell me
how to connect an audio in one this or give me a schematic for a low
voltage preamp using a single 12AU7 tube, I'd be grateful

Thanks
Dave

Oops, forgot the link to the preamp kit,
http://secure.oatleyelectronics.com//product_info.php?products_id=722

They do have (had) another similar preamp with an audio input, but
none are in stock now (discontinued)

Can you upload the regen schematic to a picture host and post the link?

http://www.oldradios.co.nz/hikers/, it's the 1951 Improved Hiker's one
valve

Replace the headphones with a logarithmic pot - the kit instructions should
indicate the resistance value to use, you need to make sure the pre-amp's
input capacitor's working voltage is rated to withstand the full HT on the
regen, or you could add a coupling capacitor to the pot's wiper.
Click to expand...
I just built a two transistor (BC549,BC558) preamp kit that works
well, will use that. I have a question regarding another regen I
have. The 45 volt HT is placed across the headphone terminals, how
would I connect an IC based amp to the radio, without frying the chip?

Schematic of the radio is at http://www.schmarder.com/radios/tube/1-30.htm
(bottom of page, not my website). Nice looking vintage style radio,
the top corners have been rounded off since (not by me), updated
pictures are @ http://www.flickr.com/photos/ozguy89/

Dave
Australia
 
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