Searching \ for '[EE] Relay coil diode specifications' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/io/motors.htm?key=relay
Search entire site for: 'Relay coil diode specifications'.

Exact match. Not showing close matches.
PICList Thread
'[EE] Relay coil diode specifications'
2006\05\31@032423 by Goran Hosinsky

picon face
What voltage and current specifications should the diode
across the relay coil have for a relay pulling 400 mA at
15V dc?
Goran, La Palma

2006\05\31@044836 by Steven Howes

picon face
I have never had any problem with just 'grabbing a diode' and using it.
I may be wrong but for the amount of time its going to be carrying
current it may not matter much. Do correct me if I am wrong and have
just been lucky previously.

Steve

-----Original Message-----
From: spam_OUTpiclist-bouncesTakeThisOuTspammit.edu [.....piclist-bouncesKILLspamspam@spam@mit.edu] On Behalf
Of Goran Hosinsky
Sent: 31 May 2006 08:24
To: Microcontroller discussion list - Public.
Subject: [EE] Relay coil diode specifications

What voltage and current specifications should the diode
across the relay coil have for a relay pulling 400 mA at
15V dc?
Goran, La Palma

2006\05\31@053736 by Wouter van Ooijen

face picon face
> What voltage and current specifications should the diode
> across the relay coil have for a relay pulling 400 mA at
> 15V dc?

A coil tries to maintain its current, so when the driver switches off
the current will be 400mA. When the driver is switched on the diode will
see a reverse voltage of 15V.

So a 15V/400mA diode would do. But I would pick an 1N4004, becase that
is my 'mid-current' yellybean diode.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


2006\05\31@073830 by olin piclist

face picon face
Wouter van Ooijen wrote:
> So a 15V/400mA diode would do. But I would pick an 1N4004, becase that
> is my 'mid-current' yellybean diode.

As long as the relay is not going to get turned on again before the current
from the last on phase decays and the diode turns off.  The reverse recovery
time of 1N4004 is rather slow, so otherwise you get some nasty effects if
you turn the switch on while the diode is still conducting.


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2006\05\31@081610 by Wouter van Ooijen
face picon face
> > So a 15V/400mA diode would do. But I would pick an 1N4004,
> becase that
> > is my 'mid-current' yellybean diode.
>
> As long as the relay is not going to get turned on again
> before the current
> from the last on phase decays and the diode turns off.  The
> reverse recovery
> time of 1N4004 is rather slow, so otherwise you get some
> nasty effects if
> you turn the switch on while the diode is still conducting.

What would be a sure-reliable suggestion? something like an 1N5819?

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


2006\05\31@102613 by Russell McMahon

face
flavicon
face
> What would be a sure-reliable suggestion? something like an 1N5819?

BYV26C (suffix varies depending on voltage) is very nice - but a
1N400x usually suffices.

       RM.


2006\05\31@120437 by olin piclist

face picon face
Wouter van Ooijen wrote:
> What would be a sure-reliable suggestion? something like an 1N5819?

A schottky would better for spped if the voltage is low enough and the
leakage acceptable (which I think is the case here).

However I would probably make sure in the firmware that there is always a
minimum off time for each relay to guarantee the diode is off before the
relay is switched on again.


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2006\05\31@151746 by Peter

picon face

On Wed, 31 May 2006, Wouter van Ooijen wrote:

>>> So a 15V/400mA diode would do. But I would pick an 1N4004,
>> becase that
>>> is my 'mid-current' yellybean diode.
>>
>> As long as the relay is not going to get turned on again
>> before the current
>> from the last on phase decays and the diode turns off.  The
>> reverse recovery
>> time of 1N4004 is rather slow, so otherwise you get some
>> nasty effects if
>> you turn the switch on while the diode is still conducting.
>
> What would be a sure-reliable suggestion? something like an 1N5819?

Either that or 1N4004 and series RC snubber in parallel to slow the
pulse down a little so the 1N4004 can cope with it. The 1N4004 is not
just slow, it has a relatively large Rs which causes the reverse voltage
to be much higher than you think it is, at least initially. This will
result in an impressive narrow peak that can raise as much as 1/2 Vcc
(in the conduction direction of the diode of course). The series RC
snubber will deal with that.

Peter

More... (looser matching)
- Last day of these posts
- In 2006 , 2007 only
- Today
- New search...