the smashed 8i resto project of sorts

[1ajs]

when ur saying + v i was not picking up on those spots on the board ur talking about never even occured to me sorry its a searious of stupid questions from someone whos very green. gotta start somewhere

 

[vrs42]

gotta start somewhere

Sure enough. You've built a simple circuit already with a single current path through the 1500 ohm resistor and the LED. This one adds the transistor's C-E path to that previous circuit, so that the transistor can turn the LED on and off. The transistor's B-E path tells it when to do that, so we connect that (via the B) lead to a resistor that provides some current from +5V. These two paths (to the B lead, and to the C lead) can come from the same supply (+5V), but in a real PDP-8 they don't. Hence the talk about +V and +5V.

In this way, signals coming from the logic of the PDP-8 would control the lamp circuits. With real incandescent lamps, +15V was used, and the lamp board drew a lot of power (about 3 amps, or 45 watts, if you could somehow light all the bulbs at once).

Vince

 

[1ajs]

does this look right?

ground is to -V

+v goes to power supply

wire in hand touching pin goes to 470 ohm resistor then to power supply

not all the pins seem to do anything?

 

[vrs42]

does this look right?

Looks great.

not all the pins seem to do anything?

Correct, but it should be possible to light every LED.

Vince

 

[1ajs]

havent had succes with lighting them all at once is there a specific pin to suggest trying?
or is it i dont have enough amps voltage to do it?

https://www.youtube.com/watch?v=AkZSF4YaYaU

 

[vrs42]

havent had succes with lighting them all at once is there a specific pin to suggest trying?

With a bulb panel, there's a trick where you power it up backwards and all the lamps light. That won't work for you because the LEDs will only pass current in the correct direction.

So one at a time is all you get, unless you can fit a connector and then apply current to several transistor base leads at once.

Vince

 

[1ajs]

That makes sens that part about led's I was aware of

With a bulb panel, there's a trick where you power it up backwards and all the lamps light. That won't work for you because the LEDs will only pass current in the correct direction.

So one at a time is all you get, unless you can fit a connector and then apply current to several transistor base leads at once.

Vince

 

[1ajs]

been stalled due to money but its not dead.

was back at the seen of the crime last night foud parts of the display panel part of 2 actualy thats

 

[1ajs]

so looking at my panel parts i noticed ones a vinyl overlay instead of painted

debating if i should leave the mud on the smashed panel parts or clean them opinions?
(rods reproduction in the background)

the collection as it stands minus the tub of cards and such

 

[1ajs]

went back in daylight found more parts

 

[1ajs]

decided to clean the board that survived in one piece

dunno if i should make a template and make a new one or reuse it? cleaned up nicely curently got it wraped in a towel under some weight to stop it from curling as it drys as i found it burried in mud witch it spent last summer and this past winter under

the rest of what i found allot more work to do seems to be spread out over a 400 sqft area with with soap decaying paper and all sorts of industrial scrap metal bits

 

[m_thompson]

The core memory stack is worth keeping.

 

[Bassoonbloke]

If the core memory stack is anywhere near repairable it may well still contain its contents, so you can see what was last running on the poor old thing.
I must admit that i'm impressed with the progress so far.
Keep up the good work.

Alan.

 

[1ajs]

thats only an end card of a core stack

 

[m_thompson]

thats only an end card of a core stack

Too bad. :-(

 

[1ajs]

ive got core stack last yr thats mangled but enough survived to hang on the wall

more pics here
https://www.flickr.com/photos/1ajs/albums/72157651577592077

 

[1944GPW]

With the lights mask board, sure you could fab up a new one. But there's something satisfying about bringing an old piece of rubbish back into use. As a vintage vehicle restorer I get the same feeling cleaning up a rusty piece of junk from a farm or fleamarket and installing it, sometimes replacing a repro part. You could take the fittings off the broken board and use them on the complete board.

Since the boards appear to have been outside for a long time already, you could give them a quick (not soak) wash to get the dirt off, then whilst still damp, clamp it under weight as you are already doing. If your hackerspace has a multi-ton press then you could press it between two pieces of steel plate or very thick hardwood planks until it dries out whilst under pressure. At your hackerspace you will find some industrious folks there to provide some ideas and advice.

 

[1ajs]

My hackerspace is.made up of software guys they all think Im crazy for.my.computer project my.local maker space is 150-200$ a month for a membership

 

[1ajs]

Yes there's something to reusing old parts when possible.

Lucked out on getting these.

Now I need to go back with a shuvil and sift more hopefully I can find more parts of the 2 broken panels would be nice to make a wall hanging of them

 

[1ajs]

still has a small curve to it but i was able to unscrew the busted studds out of the pressed brass nuts but taking a dremal to it and cuting a notch into them