[Techlunch] Line speaker transformer

Tue Sep 1 21:44:26 EST 2015

While researching this I came across one of these very transformers 
kicking around in my bench top drawer that is full of tools.
It's probably been there for 15 years or so.
Somewhat replaced by the small switch-mode wall warts now.

Neil
VK1NP

On 1/09/2015 9:35 PM, techlunch at happy.emu.id.au wrote:
> Hello Paul, Amanda, an' all,
>
> Thankyou for all the help on this one.
> My keyboard or something must have an intermittent fault as it typo'd 
> the original stock item number stamped on the transformer!! Was 
> originally described as M-2480 but actually is M-2840.
> So I think Neil has got it right "there is a M-2840 in pretty much all 
> of them (DS catalogues) but this is a 240V to 9V CT 150 mA 1.4VA"
> And strange as it may seem Jaycar's catalogue item number MM2107 is 
> described as "9V 1.35VA 150mA Centre Tap - Type 2840 Transformer"
>
> So now I'm a bit disappointed that for about 10 years I've been happy 
> knowing I've got a couple of handy line speaker transformers in the 
> bottom of the drawer if I ever need them but now  I've actually only 
> got a bit of landfill ( or free to good home )   :-(
>
> Cheers
> Bill 2WK
>
>
> On 30/08/2015 10:23 PM, techlunch at happy.emu.id.au wrote:
>> Hi Amanda,
>>
>> The blue/brown colour code of the primary winding is a pretty good 
>> indicator that it is most likely of the 230-249 volt AC mains variety.
>>
>> Slap some volts on to it (preferably via a Variac) and measure what 
>> comes out of the secondary.
>>
>> If it's a 9-0-9 type, I think that it would deliver a bit more than 
>> 150mA. Unless of course it's a very small trany.
>>
>> Cheers for now,
>> Paul 5BX
>>
>>
>> -----Original Message-----
>> From: techlunch-bounces at happy.emu.id.au 
>> [mailto:techlunch-bounces at happy.emu.id.au] On Behalf Of 
>> techlunch at happy.emu.id.au
>> Sent: Sunday, 30 August 2015 8:34 PM
>> To: techlunch at happy.emu.id.au
>> Subject: Re: [Techlunch] Line speaker transformer
>>
>> G'day Paul,
>> Tongue still in cheek!
>> It looks like a small mains transformer Blue/Brown (mains type) on 
>> one side 3 black on the other side.
>> My guess 9-0-9 may be @ 150Ma or so,
>> Cheers,
>> Amanda
>>
>> Sent from my iPad
>>
>>> On 28 Aug 2015, at 12:02 am, techlunch at happy.emu.id.au wrote:
>>>
>>> A safer thing to do would be to connect say 6 VAC to the low voltage 
>>> winding and measure what comes out of the primary.
>>>
>>> If it's a small speaker transformer, it may draw a bit of current 
>>> even at the 6 volt 50 Hz level as that may well be its lower 
>>> frequency limit. If it's a mains transformer for the Oz market, then 
>>> its design frequency will of course be 50 Hz.
>>>
>>> Paul 5BX
>>>
>>> -----Original Message-----
>>> From: techlunch-bounces at happy.emu.id.au
>>> [mailto:techlunch-bounces at happy.emu.id.au] On Behalf Of
>>> techlunch at happy.emu.id.au
>>> Sent: Thursday, 27 August 2015 6:10 PM
>>> To: techlunch at happy.emu.id.au
>>> Subject: Re: [Techlunch] Line speaker transformer
>>>
>>> Be brave Bill,
>>> If you reckon you have identified the primary, plug it in to 240V 
>>> measure what volts.
>>> Worst that can happen is a bad small or a bang!!!!!!!!
>>> Cheers
>>> Amanda
>>> PS bring it to lunch tomorrow, someone might recognise it.
>>>
>>> Sent from my iPad
>>>
>>>> On 26 Aug 2015, at 11:37 pm, techlunch at happy.emu.id.au wrote:
>>>>
>>>> Rob, Neil, Amanda,
>>>>
>>>> Thanks for looking all this up.  It looks like they are definitely 
>>>> mains transformers.
>>>> I think I may have picked them up out of a clearance box many (more 
>>>> than 10 ) years ago and always thought they were line transformers !!
>>>>
>>>> So now what am I going to do with them??
>>>>
>>>> By the way, does anyone know when Gilbert gets home? I've got a 
>>>> couple of packets of drills here for him, and they're getting boring.
>>>>
>>>> cheers
>>>> Bill
>>>>
>>>>
>>>>> On 26/08/2015 9:55 AM, techlunch at happy.emu.id.au wrote:
>>>>> Bill,
>>>>> M2480 sounds like a mains transformer.
>>>>> 100V line transformer are usually pair of wires on The low Z (8ohms)
>>>>> On the primary three spade terminals marked c  common, 5k/2.5W, 
>>>>> 2.5k/5.0W typical.
>>>>> I have only seen wires on both sides of 100V line transformers for
>>>>> high power transformers 30W Plus.
>>>>> Cheers,
>>>>> Amanda
>>>>>
>>>>> Sent from my iPad
>>>>>
>>>>>> On 25 Aug 2015, at 9:38 pm, techlunch at happy.emu.id.au wrote:
>>>>>>
>>>>>> Dear gentle folk,
>>>>>>
>>>>>> Does anyone have an old (real old) Dick Smith catalogue? You 
>>>>>> know, the ones that used to have real information in them!!
>>>>>>
>>>>>> I have a couple of transformers, which I'm pretty sure are 70V/ 
>>>>>> 100V / 8Ω.  The stock item number is M-2480.
>>>>>> The 8Ω side is obvious, but there are 3 wires on the HV side, so 
>>>>>> not sure exactly how its configured!!
>>>>>>
>>>>>> cheers
>>>>>> Bill
>>>>>>
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