[vcf-midatlantic] Robots and Relays and Commodore

[Dan Roganti]

On Wed, May 25, 2016 at 3:16 PM, Chris Fala via vcf-midatlantic <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:

> On Wed, May 25, 2016 at 2:56 PM, Dan Roganti via vcf-midatlantic <
> vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
>
> > On Wed, May 25, 2016 at 1:47 PM, Chris Fala via vcf-midatlantic <
> > vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> >
> > > On Wed, May 25, 2016 at 12:58 PM, Dan Roganti via vcf-midatlantic <
> > > vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> > >
> > > > On Wed, May 25, 2016 at 12:31 PM, Chris Fala via vcf-midatlantic <
> > > > vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> > > >
> > > > > Would this help?
> > > > >
> > > > > http://www.ebay.com/itm/152084733487
> > > > >
> > > >
> > > >
> > > > ​almost,
> > > > that one has 6 outputs
> > > > you need one with 10 outputs​
> > > >
> > >
> > >
> > > Thought the C64 user port only had an 8-bit port. Where are the other
> two
> > > connected? The VIC has a few of the joystick port connected to the user
> > > port, but not sure what other outputs you can get out of the C64.
> > >
> >
> >
> > The C64 cartridge board used a cmos 4028, 4bit BCD decoder​ [Binary Coded
> > Decimal] which has 10 outputs.
> > Even though the interface uses a 4bit binary number, the 4028 only
> converts
> > the first 10 numbers, 0-9
> > This in turn drives each motor arranged in a bridge circuit inside the
> arm.
> > There are 5 motors in the arm  = base, shoulder, elbow, wrist, and
> gripper
> > Each pair of outputs drive one motor
> > The bridge circuit is wired for each motor with a split bipolar power
> > supply using batteries, B+, Gnd, and B-
> > Only one output on the 4028 is allowed to turn on
> > As there is no protection against faulty data switching on both signals
> and
> > causing a meltdown inside the arm
> > Dan
> >
>
> OK. So only one output can be on at any one time with this setup? Kind of a
> 74141 without the high voltage?
>
> Funny thing, I Googled 4028 without any other text and the datasheet was
> the first search result.
>

Kinda, the 4028 doesn't have high voltage outputs either, but it's cmos so
it has a wider operating voltage.
As I mentioned in the other thread, they use bipolar output transistors​ on
each output of the 4028 for this.
This can waste more power, reducing the torque on the motors, they weren't
thinking ahead, it's a toy, just make it cheap and get it out the door.