|1-Build yer own...


|2-Stereo Mixer






|1-for a mind-bogglin' £8!



              Another "Cheap Bastards D.I.Y" by Phil!/Neĝ

 Yup  another  great  circuit from Phil!95 that nobody will bother with!
Actually  this  one's  pretty  good  this  time honest!  I'm not talking
cobblers,  it  works 100% - I've made it myself!  If that doesnt instill
you with confidence - nothing will!
^20^^35
                So   what   is  it  exactly?   Its  a  3  source  stereo
                mixer/fader  unit.   It  has phono sockets to connect to
                the  outputs  from  CD  players, Amigas, camcorders etc.
                The  levels  of  each  input source can be independantly
adjusted  and  all the signals are combined at the output to be fed into
yer amp / recording device.  It also features a booster on the 3rd input
to  compensate  for  source  signals that are lower in voltage than they
should  be  (IE:The  Amiga!).  You could of course just use this for the
source you intend to be most dominant...

 The  circuit  uses  just  one IC and a few other cheap components.  You
could  use  normal  'rotational'  stereo  potentiometers  instead of the
slider   pots   -  they're  easier  to  mount  but  obviously  arent  as
'professional'.   The  circuit  is  powered from 9v-12v DC regulated.  A
regulator  circuit  is  included but a PP3 battery should do if the unit
isnt going to be used for hours on end!

                       Components and Price Guide
                       --------------------------

                  1 x TL072CN Dual OpAmp IC.    (58p)
                  4 x 100K 0.25 watt resistor.  (12p)
                  8 x 330K 0.25 watt resistor.  (24p)
                  2 x 150K 0.25 Watt resistor.   (6p)
                  6 x 0.47uf Capacitor.        (180p)
                  2 x 1 uf Capacitor.           (28p)
                  3 x 47K Stereo Slider Pots. (~300p)
                  3 x stereo phono sockets-6way (75p)
                  1 x stereo phono sockets-2way (36p)

                  NB: I used electrolytic capacitors
                  but you should be able to use non-
                  polarized types such as 'Polyester
                  layer.'

The  prices  are  approx  and parts are generally available from Maplins
etc.   The  only  parts  that Maplin dont sell are the 47K stereo slider
pots  but  you should have no trouble aquiring these from other sources.
(Use 50K pots if thats all thats available.)

 You'll  also need a box to mount it in.  I used an ABS project box with
screw  down  lid.  You might wanna mount the sliders on the lid so check
the  size  of  yer  sliders and make sure the box is deep enough for the
rest  of  the  gubbings.   Making the slots for the sliders' tag to pass
through is a bit tricky unless you've got a milling machine handy(!).  A
jigsaw is probably a bit too savage for the job so try drilling a series
of  holes  along the length of the slot and filing through with a needle
file.

 I've supplied a 'proper' circuit diagram and a simplified diagram which
shows  the  physical  appearance  of  the components and the connections
between them more clearly.  Good luck!

Fin.