the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
icon

What Size Capacitor for 2 Minuite Output?


Post ReplyPost New Topic
< Prev Topic Next Topic >
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: February 19, 2015 at 11:11 PM / IP Logged  
So a cut off circuit 2 minutes after IGN off?
So a recently oft posted latching relay circuit with a 2 minute IGN off delay timer... maybe an RC fed MOSFET that breaks the relay's 85 to GND...
tmacie 
Member - Posts: 35
Member spacespace
Joined: August 22, 2005
Location: United States
Posted: February 20, 2015 at 8:45 AM / IP Logged  
Basically, yes. Its for a pre-heater for fuel filters on a diesel pickup.
I need to jump in the truck, push the button for the heaters to come on. They need to shut off after 2 minutes, unless the truck is running, then they stay on constantly. Once the truck shuts off the heaters need to shut off (they can stay on for the 2 minutes, for ease of design).
Travis
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: February 20, 2015 at 9:04 AM / IP Logged  
That's another change - albeit possibly pedantic...
Do the heaters stay on once triggered as long as the IGN is on (plus 2 minutes), or once triggered as long as the engine is running (within 2 minutes, plus 2 minutes after engine off)? I assume the latter.
Point being, if the engine stalls - or is not started - should or can the heaters stay on?
tmacie 
Member - Posts: 35
Member spacespace
Joined: August 22, 2005
Location: United States
Posted: February 20, 2015 at 9:13 AM / IP Logged  
Not really a change in design but different wording.
The longest I want the heaters to stay on is 2 min (approx.) without the truck running.
Think of it operating just like the original diagram I posted with a 2F cap, as you suggested.
Travis
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: February 20, 2015 at 9:34 AM / IP Logged  
Yeah, so it isn't IGN controlled, but "engine running" controlled.
Does it have a charge light or switched/sensed airflap or electronic injection or electrical tacho signal?
tmacie 
Member - Posts: 35
Member spacespace
Joined: August 22, 2005
Location: United States
Posted: February 20, 2015 at 9:39 AM / IP Logged  
Ok, I'll simplify it a bit now that I fully understand what you are asking.
If the key is on, the heaters can stay running.
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: February 20, 2015 at 10:17 AM / IP Logged  
Ok, so the latching SPST relay I've recently described in other threads with relay power from (fused) battery +12V and the "on" pushbutton from IGN +12V. The off button can be omitted.
The relay powers the heaters and a timer circuit. The timer relay is normally closed between GND & 85 of the latching relay.
The timer is triggered by the -ve going IGN off signal. When 2 minutes is up, the timer relay opens to de-energise the latching relay which also disconnects the timer (and reconnects latching relay 85 to GND).
The timer trigger (to IGN +12V) must handle +12V despite the timer being unpowered, otherwise the timer needs to be powered from IGN +12V.
Another job suited to a PICAXE 08...
tmacie 
Member - Posts: 35
Member spacespace
Joined: August 22, 2005
Location: United States
Posted: February 20, 2015 at 4:10 PM / IP Logged  
I think I'm following you. Just to be clear, I can use a pushbutton to activate the timer before the key is on, correct?
I'll look into the picaxe 08....
Thanks,
Travis
tmacie 
Member - Posts: 35
Member spacespace
Joined: August 22, 2005
Location: United States
Posted: February 20, 2015 at 5:08 PM / IP Logged  
Also, can you link me to the SPST relay diagram you are speaking of? Is it one of the ones in the list?
Thanks,
Travis
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: February 20, 2015 at 8:13 PM / IP Logged  
latching relay? tho that may no longer be relevant...
No - I have been describing an IGN-on system.
If you want an anytime trigger then that's a +12V (constant; battery) timer.
IMO that's easiest as separate timer tho the heater may share the same relay (ie, diode connect signal outputs to relay 86).
Chances are that whatever suitable timer you find can be used for both, or a single timer used with appropriate control logic/circuitry.
But look at the (PICAXE) 08M2. Tho it requires serial interface programming plus input/output circuitry plus the programming learning curve (ie, hack existing PICAXE web projects) it overcomes any standby consumption problems (it takes something like 14uA as opposed to the 10mA used by 555 timers etc) and is infinitely configurable. EG - one output and 5 inputs; easy to add conditions like "if engine not started or it stalls, turn off after n minutes"; etc.   
There are also Arduinos & Stamps etc tho IMO they are overkill when a thumbnail sized 08M2 can to the same.
Page of 2

Sorry, you can NOT post a reply.
This topic is closed.

  Printable version Printable version Post ReplyPost New Topic
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum

  •  
Search the12volt.com
Follow the12volt.com Follow the12volt.com on Facebook
Friday, January 27, 2023 • Copyright © 1999-2023 the12volt.com, All Rights Reserved Privacy Policy & Use of Cookies
Disclaimer: *All information on this site ( the12volt.com ) is provided "as is" without any warranty of any kind, either expressed or implied, including but not limited to fitness for a particular use. Any user assumes the entire risk as to the accuracy and use of this information. Please verify all wire colors and diagrams before applying any information.

Secured by Sectigo
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
Support the12volt.com
Top
the12volt.com spacer
the12volt.com spacer