serial port powered relay.

Serial port powered relay.

DTR ----------------o----.
| |
| / 10K
100nF === \
| / RL 50 Ohms
/ | || ______
Z0107AM __|>|______o__||____| |___
| |<| || |______| |
| || |
| 100uF 16V latching |
| bipolar relay |
GND ---------o-------------------------------'


I just threw it toogether and it worked, i'm not sure if the
values chosen are optimum.


I was able to commutate a 25A 250VAC rated relay
with a 7.5V, 50 ohm coil

the only down sidea are you need to wait 10s for the
capacitor to charge before it'll switch and the
slightly oddball parts.

On 2 Sep 2010 11:38:03 GMT, Jasen Betts <jasen_at_xnet.co.nz> wrote:


Serial port powered relay.

DTR ----------------o----.
| |
| / 10K
100nF === \
| / RL 50 Ohms
/ | || ______
Z0107AM __|>|______o__||____| |___
| |<| || |______| |
| || |
| 100uF 16V latching |
| bipolar relay |
GND ---------o-------------------------------'


I just threw it toogether and it worked, i'm not sure if the
values chosen are optimum.


I was able to commutate a 25A 250VAC rated relay
with a 7.5V, 50 ohm coil

the only down sidea are you need to wait 10s for the
capacitor to charge before it'll switch and the
slightly oddball parts.


---
How do you unlatch it?

---
JF
I think that is one of those ratchet relay's..

Whats the Z0107AM? The only hit I got when I googled it was your
post.

On 2 Sep 2010 11:38:03 GMT, Jasen Betts <jasen_at_xnet.co.nz> wrote:

Serial port powered relay.

DTR ----------------o----.
| |
| / 10K
100nF === \
| / RL 50 Ohms
/ | || ______
Z0107AM __|>|______o__||____| |___
| |<| || |______| |
| || |
| 100uF 16V latching |
| bipolar relay |
GND ---------o-------------------------------'


I just threw it toogether and it worked, i'm not sure if the
values chosen are optimum.


I was able to commutate a 25A 250VAC rated relay
with a 7.5V, 50 ohm coil

the only down sidea are you need to wait 10s for the
capacitor to charge before it'll switch and the
slightly oddball parts.

---
How do you unlatch it?

---
JF

In article <bb058c21-8110-456b-a8c3-d2a75057d68c_at_l6g2000yqb.googlegroups.com>,
George Herold <ggherold_at_gmail.com> wrote:
Whats the Z0107AM? The only hit I got when I googled it was your
post.

Looks to be a small triac from Philips/NXP. The -AM is the package suffix,
maybe just a typo for Z0107MA, which is a SOT54 aka TO92 package.

On 2 Sep 2010 11:38:03 GMT, Jasen Betts <jasen_at_xnet.co.nz> wrote:

Serial port powered relay.

DTR ----------------o----.
| |
| / 10K
100nF === \
| / RL 50 Ohms
/ | || ______
Z0107MA __|>|______o__||____| |___
| |<| || |______| |
| || |
| 100uF 16V latching |
| bipolar relay |
GND ---------o-------------------------------'

the only down sidea are you need to wait 10s for the
capacitor to charge before it'll switch and the
slightly oddball parts.

---
How do you unlatch it?

On 2010-09-02, John Fields <jfields_at_austininstruments.com> wrote:
On 2 Sep 2010 11:38:03 GMT, Jasen Betts <jasen_at_xnet.co.nz> wrote:

Serial port powered relay.

DTR ----------------o----.
| |
| / 10K
100nF === \
| / RL 50 Ohms
/ | || ______
Z0107MA __|>|______o__||____| |___
| |<| || |______| |
| || |
| 100uF 16V latching |
| bipolar relay |
GND ---------o-------------------------------'

the only down sidea are you need to wait 10s for the
capacitor to charge before it'll switch and the
slightly oddball parts.

---
How do you unlatch it?


Set the oposite voltage on the input.

PC serial port has a high resistance (about 1K2) and an open circuit voltage of
about +/- 11v

So if you model the input labeled DTR as a slow bipolar 11V square wave
through a 1K2 resistor you'oull see that the circuit works by charging
the big capacitor through the 10K resistor and then discharging it in
a surge through the triac when the input changes polarity.

Then you have to wait for it to charge up again.

One small nit-pick: DTR is an output.

But, in your circuit, an input, Duh!!!

---
JF

John Fields wrote:

But, in your circuit, an input, Duh!!!

---
JF

is it not the same!? output and input?

off course, there's a differency in resistance

On 03 Sep 2010 15:56:30 GMT, "Daniel Mandic"
daniel_mandic_at_hotmail.com> wrote:

is it not the same!? output and input?

---
It is not the same; an "output" drives, while an "input" is driven.

I read Jasen's post in the context of DTE when I should have been
reading it in the context of DCE.
---

off course, there's a differency in resistance ;-)

---
In this case, yes, but not in all cases.

http://en.wikipedia.org/wiki/Impedance_matching

---
JF