Thread Starter

Patient

Joined Jul 9, 2022
15
1. I use a medical therapy device that needs 72 volt ac input.
2. Need to drive the medical device from a 5 volt dc Powerbank for mobiles that are readily available in markets
3. For that, I need to somehow step up the powerbank output from 5vdc to 72volt (either ac or dc)
4. The max load current requirement of the medical device is very small of about 25 milli amps.
5. Can someone help please ...with a circuit design..or if I can buy something off the shelf readily as a solution....

Thanks
 

Alec_t

Joined Sep 17, 2013
13,045
DC-DC boost converters are widely advertised. Have you searched for one that cn handle a 5V to 72V boost?
25mA at 72V would mean 25mA * 72/5 = 360mA at 5V with an ideal converter, so the converter and power bank should be rated for at least about 500mA current draw.
 

Thread Starter

Patient

Joined Jul 9, 2022
15
DC-DC boost converters are widely advertised. Have you searched for one that cn handle a 5V to 72V boost?
25mA at 72V would mean 25mA * 72/5 = 360mA at 5V with an ideal converter, so the converter and power bank should be rated for at least about 500mA current draw.
I searched for one off the shelf but nothing available for 72 volt
 

Papabravo

Joined Feb 24, 2006
18,978
That would be a boost ratio of 72/5 =14.4
For a simple boost converter that would be impractical. The nominal duty cycle would be slightly over 93% making control and regulation extremely difficult. This means you would probably need something a bit more complicated involving a transformer. This would be a challenging project.
 

Thread Starter

Patient

Joined Jul 9, 2022
15
1
That would be a boost ratio of 72/5 =14.4
For a simple boost converter that would be impractical. The nominal duty cycle would be slightly over 93% making control and regulation extremely difficult. This means you would probably need something a bit more complicated involving a transformer. This would be a challenging project.
1. Is it possible to invert powerbank's 5vdc to 5vac first..then using a small transformer to boost it to 72vac ?
2. Or is it possible using a chopper transformer to boost 5vdc to 72 vdc ?
 

BobTPH

Joined Jun 5, 2013
5,467
Does it have to be a 5V power bank? 11.1 and 14.8V LiIon battery packs and chargers are common and would make the job much easier.
 

Papabravo

Joined Feb 24, 2006
18,978
1. Is it possible to invert powerbank's 5vdc to 5vac first..then using a small transformer to boost it to 72vac ?
2. Or is it possible using a chopper transformer to boost 5vdc to 72 vdc ?
I suppose, but each of those alternatives are challenging in their own right. Have you ever done anything like this before?
 

Thread Starter

Patient

Joined Jul 9, 2022
15
Does it have to be a 5V power bank? 11.1 and 14.8V LiIon battery packs and chargers are common and would make the job much easier.
It doesn't have to be 5vdc. I was just thinking to use my powerbank as it's mAh rating is huge that helps me when I go off the grid hiking somewhere!

But, yes 11.1/ 14.8 v Li battery pack should be great too !
 

Thread Starter

Patient

Joined Jul 9, 2022
15
72vac is strange number. What powers this device normally? Is it 120vac that could go as low as 72v?
This is a medical therapy device. Basically function of this device is to drive through the skin surface a small current of max 25 mA. To drive this amount of current across the skin surface as load takes a minimum of 72 to 75 volt dc. This works with 72 v ac too ( in that case the rectification is bypassed in the device)

Now this device is powered from wall outlet through a Transformer of 72 v ac output.

This 72 volt ac is plugged into the device..where it goes through a full wave rectification...

I just need to make the device mobile without the need to power it through a 72 volt ac wall adapter.
 

ronsimpson

Joined Oct 7, 2019
2,250
Does the 5 to 72 power supply need to current limit at 25ma? Last time I made this, we needed adjustable voltage and adjustable current limit.
 

Thread Starter

Patient

Joined Jul 9, 2022
15
Currently the device runs from a 72 volt ac wall adapter. If the voltage is at 72 fixed, no need of current limit. ...
Just want to replace the ac wall adapter with a dc supply source .... so that I can be mobile and go for walking ..running etc while using the device.
 
Top