Q: simple way to switch between 6 eproms?

[John Woodgate]

I read in sci.electronics.design that Eddy <gatezeddy@hotmail.com> wrote
(in <97e43a5a.0312121908.a635feb@posting.google.com&gt about 'Q: simple
way to switch between 6 eproms?', on Fri, 12 Dec 2003:

John Fields <jfields@austininstruments.com> wrote in message news:<v5njtv0rp7vbb
ajqhk9f7fcrfqe0deaisb@4ax.com>...
On 11 Dec 2003 21:48:20 -0800, gatezeddy@hotmail.com (Eddy) wrote:


Hi John,
I haven't received the schem yet, please try both my emails
thanks again

---
I sent it to your gatezeddy@hotmail.com address; if that's wrong or you
want me to post it somewhere else please post the other address(es)

John, please try nspy@NOSPAMexcite.com as I still haven't received it
at hotmail. discard nospam..

Doesn't Hotmail strip off attachments?

--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

 

[Eddy]

John Woodgate <jmw@jmwa.demon.contraspam.yuk> wrote in message news:<6dcLxUD+Jv2$Ewia@jmwa.demon.co.uk>...

I read in sci.electronics.design that Eddy <gatezeddy@hotmail.com> wrote
(in <97e43a5a.0312121908.a635feb@posting.google.com&gt about 'Q: simple
way to switch between 6 eproms?', on Fri, 12 Dec 2003:
John Fields <jfields@austininstruments.com> wrote in message news:<v5njtv0rp7vbb
ajqhk9f7fcrfqe0deaisb@4ax.com>...
On 11 Dec 2003 21:48:20 -0800, gatezeddy@hotmail.com (Eddy) wrote:


Hi John,
I haven't received the schem yet, please try both my emails
thanks again

---
I sent it to your gatezeddy@hotmail.com address; if that's wrong or you
want me to post it somewhere else please post the other address(es)

John, please try nspy@NOSPAMexcite.com as I still haven't received it
at hotmail. discard nospam..

Doesn't Hotmail strip off attachments?

Got it John, thanks again for your help!

 

[Eddy]

gatezeddy@hotmail.com (Eddy) wrote in message news:<97e43a5a.0312131653.60b4e45e@posting.google.com>...

John Woodgate <jmw@jmwa.demon.contraspam.yuk> wrote in message news:<6dcLxUD+Jv2$Ewia@jmwa.demon.co.uk>...
I read in sci.electronics.design that Eddy <gatezeddy@hotmail.com> wrote
(in <97e43a5a.0312121908.a635feb@posting.google.com&gt about 'Q: simple
way to switch between 6 eproms?', on Fri, 12 Dec 2003:
John Fields <jfields@austininstruments.com> wrote in message news:<v5njtv0rp7vbb
ajqhk9f7fcrfqe0deaisb@4ax.com>...
On 11 Dec 2003 21:48:20 -0800, gatezeddy@hotmail.com (Eddy) wrote:


Hi John,
I haven't received the schem yet, please try both my emails
thanks again

---
I sent it to your gatezeddy@hotmail.com address; if that's wrong or you
want me to post it somewhere else please post the other address(es)

John, please try nspy@NOSPAMexcite.com as I still haven't received it
at hotmail. discard nospam..

Doesn't Hotmail strip off attachments?



Got it John, thanks again for your help!

John, wired the cct exactly as per your schem, it works fine except it
switches thru and lights all 8 outputs, all the LED's come ON
sequentially..its not a bad thing but its supposed to reset at the 6th
LED, any suggestions as to why this is happening? it makes sense that
when output5 goes LO, it resets the /load on the '161 but it doesn't
reset it, it continues on to light output6(LED7), & output7(LED8)

thanks
Ed

 

[John Fields]

On 15 Dec 2003 20:18:02 -0800, gatezeddy@hotmail.com (Eddy) wrote:

John, wired the cct exactly as per your schem, it works fine except it
switches thru and lights all 8 outputs, all the LED's come ON
sequentially..its not a bad thing but its supposed to reset at the 6th
LED, any suggestions as to why this is happening? it makes sense that
when output5 goes LO, it resets the /load on the '161 but it doesn't
reset it, it continues on to light output6(LED7), & output7(LED8)
---

What I suspect is happening is that you have either forgotten to connect
U3-10 to U2-9 or that when DS6 is lit, the current going into U3-10 is
high enough to keep the voltage on U3-10 from falling close enough to
ground to allow U2 to load on the rising edge of the next clock. If
it's not a wiring error there are two [easy] fixes, the first being to
substitute a lower current LED for DS6, along with a higher resistance
resistor for R8. If you use something like an HLMP-4700 (Red 2mA LED)
and a 1500 ohm resistor for R8 it should work. The second fix is to
rewire the circuit so that instead of synchronously loading zeros into
the counter you asynchronously clear it. To do that, disconnect U3-10
from U2-9, disconnect U2-1 from Vcc, then connect U2-9 to Vcc and
connect U2-1 to U3-9.

--
John Fields

 

[Eddy]

John Fields <jfields@austininstruments.com> wrote in message news:<hntttv41u44p98pdia1sg8lv3el83tdvif@4ax.com>...

On 15 Dec 2003 20:18:02 -0800, gatezeddy@hotmail.com (Eddy) wrote:


John, wired the cct exactly as per your schem, it works fine except it
switches thru and lights all 8 outputs, all the LED's come ON
sequentially..its not a bad thing but its supposed to reset at the 6th
LED, any suggestions as to why this is happening? it makes sense that
when output5 goes LO, it resets the /load on the '161 but it doesn't
reset it, it continues on to light output6(LED7), & output7(LED8)
---
What I suspect is happening is that you have either forgotten to connect
U3-10 to U2-9 or that when DS6 is lit, the current going into U3-10 is
high enough to keep the voltage on U3-10 from falling close enough to
ground to allow U2 to load on the rising edge of the next clock. If
it's not a wiring error there are two [easy] fixes, the first being to
substitute a lower current LED for DS6, along with a higher resistance
resistor for R8. If you use something like an HLMP-4700 (Red 2mA LED)
and a 1500 ohm resistor for R8 it should work. The second fix is to
rewire the circuit so that instead of synchronously loading zeros into
the counter you asynchronously clear it. To do that, disconnect U3-10
from U2-9, disconnect U2-1 from Vcc, then connect U2-9 to Vcc and
connect U2-1 to U3-9.

John,
I'm using is a 3mm red LED but I don't have the specs.
I wired exactly as the schem and tried a 1k, 1.5k and 2.2k resistor
and it didn't work. I, re-wired according to the asynchronous reset
and it works fine. It does reset to the 1st LED...thanks again

 

[John Fields]

On 17 Dec 2003 11:02:40 -0800, gatezeddy@hotmail.com (Eddy) wrote:

John,
I'm using is a 3mm red LED but I don't have the specs.
I wired exactly as the schem and tried a 1k, 1.5k and 2.2k resistor
and it didn't work. I, re-wired according to the asynchronous reset
and it works fine. It does reset to the 1st LED...thanks again

---
You're welcome.

That's pretty interesting. Since an unloaded '138 output can clear the
'161, that leads me to believe that there's something else on the EPROM
enable lines which isn't allowing the '138's loaded output to be pulled
low enough to enable the 161's /LOAD input. Just out of curiosity, if
you could measure the voltage on the 138's outputs with the LEDs lit and
unlit and post what you find that would also be interesting.

--
John Fields