[chbot] spark eroder power supply

Mark Atherton markaren1 at xtra.co.nz
Sat Nov 28 03:32:16 GMT 2020

Hi Graeme,

How are you controlling the current ?

I have some vague recollection that you were using an SCR or a TRIAC, in 
which case you need zero-crossing, so an SMPSU will not work.


On 28/11/2020 3:13 PM, Robert W. Walker,  wrote:
> Hi... There are a range of heavy duty transformers but, particularly, 
> heavy duty switch mode and regulated supplies that are commonly used and 
> are available for E-bikes, E-scooters, Mobility chairs etc. They range 
> from 12volts up to 70 volts or slightly more. Check out Google or 
> Alibaba, Aliexpress or Ebay....
> Nga mihi...
> Bob, ZL2ROB (QTHR)
> Mark Atherton wrote on 28/11/2020 12:46 pm:
>> Hi Graeme,
>> A 75V/10A transformer is a pretty specialist voltage, and while you 
>> might get lucky finding one, the idea of 3 x 24V/10A with secondaries 
>> in series sounds a more likely/lower cost option.
>> You might be able to do something clever with beefy ex-UPS 
>> transformers, but they are not going to have their windings marked so 
>> there is a possibility of injury if you wire them up wrongly.
>> Obvious places to scour include Echotech, Trademe, and Molten Media.
>> Regards,
>> Mark
>> PS Warren may also have some ideas, or something squirrelled away :)
>> On 28/11/2020 11:51 AM, Graeme Absalom wrote:
>>> Hi All
>>> I need some help. Recently I've been pondering on why my spark eroder 
>>> only delivers 3 Amps on the onboard ammeter. It hadn't worried me 
>>> before because it does work. It is rated for 10 Amp. I decided that 
>>> the transformer is far too small to deliver 10 Amps. I tried putting 
>>> in a 120 volt 12 Amp and proved that the installed transformer is not 
>>> capable but blew a power resister. Reading the book / specs again 
>>> what I need is a wire wound, iron core, 230 volts to 75 volts AC and 
>>> 10 Amp. The book uses 3 x 24volts AC 10Amp transformers in series.
>>> Does anyone know where I could get a approx 75 volt, 10 transformer?
>>> Thanks
>>> Graeme Absalom

More information about the Chchrobotics mailing list