Thanks: 0
Likes: 0
Needs Pictures: 0
Picture(s) thanks: 0
Results 1 to 8 of 8
-
19th August 2011, 04:33 PM #1Senior Member
- Join Date
- Jul 2004
- Location
- Lilydale Victoria
- Age
- 88
- Posts
- 113
Help needed electronics/electrical
Thought this forum might have most people with electronics in among their skills!
After 34 years operation the circuit board in my Kamira belt mounted power pack for the dust mask has packed up. However the fan is OK.
It has some fancy electronics to vary fan speed as activity increases,however as it is only used for woodwork would be happy to run at a fixed lower speed.
Battery pack is 4.8 v, but fan has 365mA and 3.57V on the label.
If i replaced the circuit board with a variable resistance which would allow me to adjust fan speed, to give the required flow rate, would that be OK and what spec should I be looking for.
Alternatively does anyone know a good electronics guy around Lilydale (vic), that could check out the circuit board.Last edited by Paddy; 19th August 2011 at 04:35 PM. Reason: add pics
-
19th August 2011 04:33 PM # ADSGoogle Adsense Advertisement
- Join Date
- Always
- Location
- Advertising world
- Age
- 2010
- Posts
- Many
-
19th August 2011, 05:10 PM #2Been here a while
- Join Date
- Feb 2004
- Location
- Victoria
- Posts
- 345
Not all fans can be slowed via a potentiometer. Some are pulsed, with the duty cycle controlling the speed. Also, I'm guessing the board charges the batteries? Are you replacing them as well, or have some way of charging them externally?
-
19th August 2011, 05:37 PM #3Senior Member
- Join Date
- Jul 2004
- Location
- Lilydale Victoria
- Age
- 88
- Posts
- 113
Hi sjm
Batterys are removed and charged separately.
Fan seems to run at the correct lower speed, when connected to 3.0V supply.
At the fully charged level on the powerpack (brief contact only) the fan runs faster than the normal max speed.
Have disconnected fan from circuit board for above trials
-
19th August 2011, 07:52 PM #4
You could try a voltage regulator kit like this one:
Voltage Regulator Kit - Jaycar Electronics
-
19th August 2011, 07:55 PM #5Member
- Join Date
- Dec 2007
- Location
- Home
- Posts
- 85
Motors are best controlled by 'pulse with modulation' (PWM) which is just a fancy way to describe turning things on & off quickly.
PWM is easy & cheap these days, all those cheap cordless tools have a little PWM chip in them. It might be possible to re-purpose one of those but I'm unsure they'd work at 5v. They should (in fact they should work from 3-18v). (I should check, that'd be handy to know...)
The automatically adjusting to workload part is a bit more difficult to do.
You may be able to use a resistor to limit the speed, but determining the value to use needs to be done by the trial-and-error method. The variable resistors (pots) these days aren't made to handle much current, so you can't use those unless you add a few parts.
It should be repairable, the parts it uses are fairly common.
BTW, are you sure it's 34 years old?
-
20th August 2011, 12:39 AM #6Senior Member
- Join Date
- Jul 2004
- Location
- Lilydale Victoria
- Age
- 88
- Posts
- 113
Bad maths! 24 years old bought it new in 1987.Used it whilst spraying weeds etc on the farm, current battery pack is about 9 years old.
The other thought I have just had is to build a new battery pack with 3.6 volts output , rather than the current 4.8V and just have a simple switch.Think this would give about the required fan speed and match the voltage marked on the fan.
Does that sound a reasonable solution?
-
20th August 2011, 01:48 AM #7Member
- Join Date
- Dec 2007
- Location
- Home
- Posts
- 85
Battery packs are only a bunch of rechargeable batteries anyway, so making a new one is reasonable. They are 1.2v, so your current pack has 4.
You can use common AA batteries, you can get them with 2500mAh capacity, so in theory (going on the motor current) they'd last about 6 hours (2500 / 365).
Jaycar sell holders, this one: 4 x AAA Side by Side - Jaycar Electronics holds 4 AA, but you can get ones that hold 3. You can get them with a cover & built-in switch as well: 4AA Switched Battery Enclosure - Jaycar Electronics. You can always add a 'dummy' battery to take up the 4th spot, or solder in a wire.
I'd try the repair route first, someone local with a bit of time might chip in. It may be a simple fault like a dry solder joint or loose connection, but looking at the parts it's using it's definitely fixable.
-
20th August 2011, 09:54 AM #8Senior Member
- Join Date
- Jul 2004
- Location
- Lilydale Victoria
- Age
- 88
- Posts
- 113
Thanks Dropcat
Those Jacar holders look great and will fit in the storage space OK. Was previously thinking of building my own from an old battery pack.
Will do some test runs on the workbench first
Similar Threads
-
Help needed ..Electrical
By Paddy in forum METALWORK FORUMReplies: 13Last Post: 19th February 2009, 11:01 PM -
Electrical requirements needed for workshop.
By snapman007 in forum WOODWORK - GENERALReplies: 34Last Post: 9th December 2008, 09:33 PM -
Electronics help needed
By gaffa in forum CNC MachinesReplies: 8Last Post: 19th September 2008, 11:05 AM