Welcome, Guest. Please login or register.

Author Topic: Mystery Component on CD32 Joypad Schematic  (Read 3582 times)

Description:

0 Members and 1 Guest are viewing this topic.

Offline XamicheTopic starter

Mystery Component on CD32 Joypad Schematic
« on: April 10, 2008, 06:42:12 AM »
I'm just about to order the parts required to build the below circuit, however there is one component I am not familiar with. It's the TL1 component in the circuit. I'm wondering if any of the electronics savvy members can tell me what it is?

A500, A600, A1200, A2000, A4000D, A4000T, CD32
 

Offline Castellen

Re: Mystery Component on CD32 Joypad Schematic
« Reply #1 on: April 10, 2008, 06:56:54 AM »
It's just an RF suppression choke.  It provides a high impedance to RF signals (looking at the image, I'd estimate from around 50MHz upwards).

To cut a long story short, it isn't necessary for the circuit to work.  TL1 reduces emissions from the circuit above a certain frequency, and provides some immunity from RF radiated into the connecting cable from an external source.  From a design point of view, it seems strange why you'd include this into one of the external lines, but not the others.

I'd suggest not fitting TL1.  But it's usually good design practice to fit a 1nF (or whatever) ceramic capacitor between each external signal line and ground, close to where the cable enters the PCB.
 

Offline XamicheTopic starter

Re: Mystery Component on CD32 Joypad Schematic
« Reply #2 on: April 10, 2008, 07:06:13 AM »
Many thanks for the reply and advice Castellen. :-)
A500, A600, A1200, A2000, A4000D, A4000T, CD32
 

Offline Chain

  • Hero Member
  • *****
  • Join Date: Jun 2005
  • Posts: 1324
    • Show only replies by Chain
    • http://chain.3dgrafika.cz/aktivity
Re: Mystery Component on CD32 Joypad Schematic
« Reply #3 on: April 10, 2008, 07:12:43 AM »
i think it acts together with 470p capacitor as LC band rejection filter
too lazy to use shift key properly...
 

Offline XamicheTopic starter

Re: Mystery Component on CD32 Joypad Schematic
« Reply #4 on: April 10, 2008, 02:35:51 PM »
I'm thinking I'm going to include the component in the circuit. Only thing is, I'm not sure where to find it in the electronics catalogue I use. I buy from Altronics Australia generally, although they don't always have what I need.

Edit:
Any Australians here know of a good source of electronic components? I've tried a couple of places and none seem to carry any 74LS165s.
A500, A600, A1200, A2000, A4000D, A4000T, CD32
 

Offline Retro_71

  • Hero Member
  • *****
  • Join Date: Nov 2007
  • Posts: 732
    • Show only replies by Retro_71
Re: Mystery Component on CD32 Joypad Schematic
« Reply #5 on: April 10, 2008, 05:21:15 PM »
Have you triede JayCar  or Dick Smiths? If you get them in WA.
A Chameleon and 1541 II ultimate II
2 x C=64, 2 x C64C, C128 (jiffydos), C128D, 3 x A500 (1 x 030),
A1000, 2 x A2000 (GVP 040 + SCSI combo + indivision), A3000 GVP IV24 & Emplant
3 x A1200 (1 x 030, Indivision and IDE-Fix with 40 GB HDD & DVD Burner)
2 x A4000 (4060, Deneb, Indivsion), CD32.
2 x Apple IIe and A IIGS (Various new cards), + 3 x Megadrives (CD and 32), 2 x Saturns, and a dreamcast.. :D
 

Offline XamicheTopic starter

Re: Mystery Component on CD32 Joypad Schematic
« Reply #6 on: April 10, 2008, 08:22:50 PM »
Tried Jaycar, no joy there. I'm not sure if Dick Smith still sells those type of components. They're more an appliance/electrical store these days. Last time I was in Dick Smiths I had trouble getting caps and resistors, much less chips. I sure miss the Dick Smith and Tandy of old.
A500, A600, A1200, A2000, A4000D, A4000T, CD32
 

Offline rkauer

  • Hero Member
  • *****
  • Join Date: May 2006
  • Posts: 3263
    • Show only replies by rkauer
Re: Mystery Component on CD32 Joypad Schematic
« Reply #7 on: April 10, 2008, 10:23:44 PM »
 You can use "high speed" 74xx equivalent, like 74ALS165, 74S165 or 74HCT165.

 For the "strange" component: it is a ferrite with 6 perforations, dimensions in the schematics (diameter 6mm, 10mm in length).
Goodbye people.

I\'ll pop on from time to time, RL is acting up.
 

Offline XamicheTopic starter

Re: Mystery Component on CD32 Joypad Schematic
« Reply #8 on: April 11, 2008, 07:17:29 AM »
Quote

rkauer wrote:
 You can use "high speed" 74xx equivalent, like 74ALS165, 74S165 or 74HCT165.

 For the "strange" component: it is a ferrite with 6 perforations, dimensions in the schematics (diameter 6mm, 10mm in length).

Ahh cool. It never really occurred to me to look at using the ALS or HC 74s. Thanks :-)

Regarding the ferrite component, am I likely to find this at a regular electronic component store? I've scoured my Altronics catalogue and cannot find anything remotely like it.
A500, A600, A1200, A2000, A4000D, A4000T, CD32
 

Offline Castellen

Re: Mystery Component on CD32 Joypad Schematic
« Reply #9 on: April 11, 2008, 07:46:08 AM »
Or there's equivalent CMOS gates you can use (4000 series) which will do the same job.  They tend to have different pinouts, but nothing that 30 seconds with the datasheet can't resolve.
Either that, or do the same job using different logic.  You can just as easily use combinations of NAND or XOR gates to exactly the same job.  If you can't work it out in your head, then just write out the truth tables.

Regarding the inductor, the author hasn't even specified the type of ferrite to use (there are various different componds which react differently at different frequencies).  So the value of inductance vs frequency clearly is not important.  If you really want to put an inductor in there for whatever reason, just select any low current 100µH leaded inductor.  It's not going to make any difference.
 

Offline XamicheTopic starter

Re: Mystery Component on CD32 Joypad Schematic
« Reply #10 on: April 11, 2008, 07:59:38 AM »
Actually, I still have lecture notes on a shift register we built with flip-flops back in digi electronics. Time to do some revision I think :-D

Thanks for the advice all. :)
A500, A600, A1200, A2000, A4000D, A4000T, CD32
 

Offline Chain

  • Hero Member
  • *****
  • Join Date: Jun 2005
  • Posts: 1324
    • Show only replies by Chain
    • http://chain.3dgrafika.cz/aktivity
Re: Mystery Component on CD32 Joypad Schematic
« Reply #11 on: April 11, 2008, 11:24:40 AM »
f=1/(2*pi*sqrt(L*C))

so ie. for 1MHz band filter it will be T1L=54uH
too lazy to use shift key properly...