[neonixie-l] Re: Single inductor supplies and heat issues

[GastonP]

The usual auction site is your friend... ;)

40-50 USD each, depending on the state of disassembly of the original part, 
with free shipping.

On Thursday, November 15, 2018 at 8:40:34 PM UTC-3, orange_glow_fan wrote:
>
>
> Wow, that video is amazing!  Any idea as to what these new Nixies sell 
> for?   An arm?, leg? first born??
>
>
>
>>

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[neonixie-l] Re: Single inductor supplies and heat issues

[jörg]

Yes,
this is my prototype. 
I like the open possibilties to drive the tube directly. I get the warm display 
glow and plenty more options like showing text or graphics.

I will stresstest the PWS and post the results.

Thanks for viewing the video. I will try to make a better quality one.

Cheers,
Jörg

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Re: [neonixie-l] Re: Single inductor supplies and heat issues

[Oyvind Idland]

Forgot to mention that I have tried inductors from 100 - 270 uH range in
various frequency combinations. I also simulate stuff,
preferably using LTSpice (using TINA on most TI chips due to lack of
spice-models).

The inductors were selected to be well above the peak-peak from simulations.

Most chips can have the frequency configured easily by replacing a resistor
and/or capacitor. My experiments have been in the 40-60 kHz range.



On Thu, Nov 15, 2018 at 11:57 PM threeneurons  wrote:

> Yes, I like using the old MC34063. Its a relatively simple chip. But don't
> get stuck on the semiconductors. The coil is the main player. And real
> inductors behave a lot differently than ideal inductors. More so than
> capacitors and resistors, when comparing the ideal model with the real
> parts. For power applications, the inductance changes (to a lower value) as
> current increases. This happens well before the part goes into saturation,
> so any calculations made, are just a first stab. In reality, you may have
> to go 2 to 4 times higher, than calculated.
>
> In practical matters I like using coils with E3 values (E3 meaning
> significant figures of 10, 22 & 47). With the MC34063, I can change base
> frequency with the timing cap. Smaller caps can be found, cheaply, in a
> wider range of values (E6 - 10, 15, 22, 33, 47, & 68). E12 or higher only
> with resistors (E12 - 10,12,15,18,22,27,33,39,47,56,68,82).
>
> You can get more power out of an SDR1806, but before going there you
> aren't get all the power out of the RLB9012. If you can't easily change
> frequency, then increase the inductor size. Buy some 220uH coils, though
> you should be able to get more power out of the 100uH part. I routinely get
> more than 30mA out, at nixie voltages.
>
> On Wednesday, November 14, 2018 at 12:24:36 AM UTC-8, Oyvind wrote:
>>
>> Hi,
>>
>> first: interesting & very useful webpage ! (recognized your nickname).
>> Appreciate people who share information like that.
>>
>> Increasing frequency will only result in maxing out duty cycles. Not sure
>> if I tested the RLB on >= 60kHz yet though, I'll
>> give it a go later.
>>
>> What frequency are you at, approximately ?
>>
>> Assuming you're using the MC34063, I'm not sure how the PWM scheme looks
>> on that one. Have you tried peeling off
>> the outer shrink tube on the inductor ?  At first I didn't think there
>> was any significant heat, until I realized the shrink tube
>> was messing with me.
>>
>> Anyways, I found some nice off-the shelf transformers which looks very
>> promising in simulation, so I'm heading for
>> flyback. Slightly more expensive though, but not a concern for me.
>>
>>
>> - Oyvind
>>
>>
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[neonixie-l] Re: Single inductor supplies and heat issues

['orange_glow_fan' via neonixie-l]

Wow, that video is amazing!  Any idea as to what these new Nixies sell 
for?   An arm?, leg? first born??



>

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[neonixie-l] Re: Single inductor supplies and heat issues

[threeneurons]

Yes, I like using the old MC34063. Its a relatively simple chip. But don't 
get stuck on the semiconductors. The coil is the main player. And real 
inductors behave a lot differently than ideal inductors. More so than 
capacitors and resistors, when comparing the ideal model with the real 
parts. For power applications, the inductance changes (to a lower value) as 
current increases. This happens well before the part goes into saturation, 
so any calculations made, are just a first stab. In reality, you may have 
to go 2 to 4 times higher, than calculated.

In practical matters I like using coils with E3 values (E3 meaning 
significant figures of 10, 22 & 47). With the MC34063, I can change base 
frequency with the timing cap. Smaller caps can be found, cheaply, in a 
wider range of values (E6 - 10, 15, 22, 33, 47, & 68). E12 or higher only 
with resistors (E12 - 10,12,15,18,22,27,33,39,47,56,68,82).

You can get more power out of an SDR1806, but before going there you aren't 
get all the power out of the RLB9012. If you can't easily change frequency, 
then increase the inductor size. Buy some 220uH coils, though you should be 
able to get more power out of the 100uH part. I routinely get more than 
30mA out, at nixie voltages.

On Wednesday, November 14, 2018 at 12:24:36 AM UTC-8, Oyvind wrote:
>
> Hi,
>
> first: interesting & very useful webpage ! (recognized your nickname). 
> Appreciate people who share information like that.
>
> Increasing frequency will only result in maxing out duty cycles. Not sure 
> if I tested the RLB on >= 60kHz yet though, I'll 
> give it a go later.
>
> What frequency are you at, approximately ?
>
> Assuming you're using the MC34063, I'm not sure how the PWM scheme looks 
> on that one. Have you tried peeling off 
> the outer shrink tube on the inductor ?  At first I didn't think there was 
> any significant heat, until I realized the shrink tube 
> was messing with me.
>
> Anyways, I found some nice off-the shelf transformers which looks very 
> promising in simulation, so I'm heading for 
> flyback. Slightly more expensive though, but not a concern for me.
>
>
> - Oyvind
>
>
>>>

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[neonixie-l] Re: Single inductor supplies and heat issues

[Oyvind]

Nice ! 

Searched for "GIPS-16-1" on youtube, and found this one with that 
transformer.. so that must be you, right ? :D

https://www.youtube.com/watch?v=EBAJ10H2Ek0

How much power is it pulling ?



On Thursday, November 15, 2018 at 12:18:23 PM UTC+1, jörg wrote:
>
> I build a PWS using the DA2032. I'm very satisfied with it. The FET's and 
> Transformer warm up about max 30 degrees C. 
>
> If you like, take a look at my video, it shows the PWS driving a GIPS-16-1 
> tube. 
>
> Cheers, 
> Jörg

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[neonixie-l] Re: Single inductor supplies and heat issues

[jörg]

I build a PWS using the DA2032. I'm very satisfied with it. The FET's and 
Transformer warm up about max 30 degrees C.

If you like, take a look at my video, it shows the PWS driving a GIPS-16-1 tube.

Cheers,
Jörg

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[neonixie-l] Re: Single inductor supplies and heat issues

[petehand]

In my opinion, 100uH is a bit low for a frequency of 40-60kHz. I would use 
at least 220uH. For estimating saturation current, multiply the total load 
current by the voltage step-up and double it (since the input current is a 
triangle). So if you want 15mA at 180V from a 12V supply, you can expect a 
peak primary current of (180/12)*0.015*2 - you should be looking for an 
inductor with a saturation current of at least 0.5A.

You can ease the strain on your driver transistor by using a split coil 
inductor - the transistor only sees half the secondary voltage. This is the 
generator I use on my FLW design that can drive 50mA at 180V. 

[image: step-up.jpg]



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[neonixie-l] Re: Single inductor supplies and heat issues

[Oyvind]

>
>
> Can you share some more specifics and/or a link?
>
>
>
Sure ! Actually, I was about to order customized transformers from China 
(can be done for ~$45 for 5 pcs), when I discovered this page in the last 
moment:

https://www.coilcraft.com/prod_flyback.cfm

The specific ones are listed here:
https://www.coilcraft.com/da2032.cfm

These are 1:10, with 10uH on the primary.

The specs on DA2032 looks fine for my simulations so far, optionally DA2033 
for heavier lifting. 
I'm gonna try to increase the frequency and see how the transformer 
responds to that, in order to reduce peak to peak. 

Hopefully I get to design the PCB and order parts during this weekend... 

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[neonixie-l] Re: Single inductor supplies and heat issues

[Jon]

On Wednesday, November 14, 2018 at 8:24:36 AM UTC, Oyvind wrote:
>
> Anyways, I found some nice off-the shelf transformers which looks very 
> promising in simulation, so I'm heading for 
> flyback. Slightly more expensive though, but not a concern for me.
>

Can you share some more specifics and/or a link?

Jon.

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[neonixie-l] Re: Single inductor supplies and heat issues

[Oyvind]

Hi,

first: interesting & very useful webpage ! (recognized your nickname). 
Appreciate people who share information like that.

Increasing frequency will only result in maxing out duty cycles. Not sure 
if I tested the RLB on >= 60kHz yet though, I'll 
give it a go later.

What frequency are you at, approximately ?

Assuming you're using the MC34063, I'm not sure how the PWM scheme looks on 
that one. Have you tried peeling off 
the outer shrink tube on the inductor ?  At first I didn't think there was 
any significant heat, until I realized the shrink tube 
was messing with me.

Anyways, I found some nice off-the shelf transformers which looks very 
promising in simulation, so I'm heading for 
flyback. Slightly more expensive though, but not a concern for me.


- Oyvind

On Monday, November 12, 2018 at 9:45:51 PM UTC+1, threeneurons wrote:
>
> I think your doing something wrong. I use the RLB9012-101KL routinely, and 
> get twice the output current (~35mA @ 180V), while the coil gets warm, but 
> still within reason. I'd suggest that you increase your switching 
> frequency. I suspect you're well into saturation.
>
> On Tuesday, November 6, 2018 at 12:12:29 AM UTC-8, Oyvind wrote:
>>
>> Hi,
>>
>> I have been experimenting a bit with single inductor supplies. I built 
>> one myself based on TPS40210, and tried a couple of others too.
>>
>> Common for all, is that the inductor gets quite hot when running them on 
>> a 10K dummy load @180V. 
>>
>> So, for 6 IN-14 tubes on 1.5 mA each, they work just fine, but not much 
>> more than that.
>>
>> I tried various inductors, with fairly high amp ratings:
>>
>>
>> - shielded SMD ones have most pronounced. That is, I can hold my finger 
>> on it, but just barely.
>> - radial THT, souch as Bourns RLB9012-101KL. When peeling off the outer 
>> coating, the heat is obvious
>> - toroids with low ohms / high amps. These gives best result, but gets 
>> "luke warm".
>>
>> I'm thinking that having a supply like that inside a casing would not be 
>> good in the long run. I am aiming for non-multiplexed..
>>
>> Not sure how to remedy this (snubber or similar ?), perhaps this topology 
>> isn't the most ideal. 
>>
>>
>> What's your experiences here ?
>>
>>

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[neonixie-l] Re: Single inductor supplies and heat issues

[threeneurons]

I think your doing something wrong. I use the RLB9012-101KL routinely, and 
get twice the output current (~35mA @ 180V), while the coil gets warm, but 
still within reason. I'd suggest that you increase your switching 
frequency. I suspect you're well into saturation.

On Tuesday, November 6, 2018 at 12:12:29 AM UTC-8, Oyvind wrote:
>
> Hi,
>
> I have been experimenting a bit with single inductor supplies. I built one 
> myself based on TPS40210, and tried a couple of others too.
>
> Common for all, is that the inductor gets quite hot when running them on a 
> 10K dummy load @180V. 
>
> So, for 6 IN-14 tubes on 1.5 mA each, they work just fine, but not much 
> more than that.
>
> I tried various inductors, with fairly high amp ratings:
>
>
> - shielded SMD ones have most pronounced. That is, I can hold my finger on 
> it, but just barely.
> - radial THT, souch as Bourns RLB9012-101KL. When peeling off the outer 
> coating, the heat is obvious
> - toroids with low ohms / high amps. These gives best result, but gets 
> "luke warm".
>
> I'm thinking that having a supply like that inside a casing would not be 
> good in the long run. I am aiming for non-multiplexed..
>
> Not sure how to remedy this (snubber or similar ?), perhaps this topology 
> isn't the most ideal. 
>
>
> What's your experiences here ?
>
>

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Re: [neonixie-l] Re: Single inductor supplies and heat issues

[Oyvind]

Thanks, interesting page indeed !

- Oyvind

On Wednesday, November 7, 2018 at 7:05:57 PM UTC+1, Sgitheach wrote:
>
> I found this useful: 
>
> http://www.dos4ever.com/flyback/flyback.html 
>
> Grahame 
>

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[neonixie-l] Re: Single inductor supplies and heat issues

[Oyvind]

Yep, and there is the problem with the voltage ratio (from 12V in my case).

Flyback, or tapped inductor boost is definietly on topic :)

Coupled inductors are also made by several manufacturers. These are often 
customized for specific applications, but there are some off-the-shelf 
ones. I guess I would need something like 1:10 windings.

I find it somewhat difficult to design it though, as most literature 
describes step-down. I guess there is more to it than just slamming a 
transformer into a boost topology.


- Oyvind

On Wednesday, November 7, 2018 at 7:02:31 PM UTC+1, gregebert wrote:
>
> Be careful about simply increasing the inductance, because that can 
> actually reduce the amount of energy-per-cycle, hence the power, assuming 
> constant frequency.
>
> Energy = 1/2 LI^2, and from V = Ldi/dt , you can infer energy-per-cycle = 
> 1/2 (V^2) * (T^2)/L
>
> In other words, to increase the energy-per-cycle, you want to increase the 
> voltage or the duty-cycle.
> If your duty cycle is getting too high, change the inductor to a 
> transformer (flyback converter). A transformer is just 2 coupled-inductors, 
> and it's fairly easy to model that in SPICE.
> Be careful about the coupling factor, because it's not 1.0, and as it's 
> reduced you will see increasing spikes across your MOSFET when it switches 
> off.
>
>  
>

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Re: [neonixie-l] Re: Single inductor supplies and heat issues

['Grahame' via neonixie-l]

I found this useful:

http://www.dos4ever.com/flyback/flyback.html

Grahame

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[neonixie-l] Re: Single inductor supplies and heat issues

[gregebert]

Be careful about simply increasing the inductance, because that can 
actually reduce the amount of energy-per-cycle, hence the power, assuming 
constant frequency.

Energy = 1/2 LI^2, and from V = Ldi/dt , you can infer energy-per-cycle = 
1/2 (V^2) * (T^2)/L

In other words, to increase the energy-per-cycle, you want to increase the 
voltage or the duty-cycle.
If your duty cycle is getting too high, change the inductor to a 
transformer (flyback converter). A transformer is just 2 coupled-inductors, 
and it's fairly easy to model that in SPICE.
Be careful about the coupling factor, because it's not 1.0, and as it's 
reduced you will see increasing spikes across your MOSFET when it switches 
off.

 

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[neonixie-l] Re: Single inductor supplies and heat issues

[Jon]

On Tuesday, November 6, 2018 at 1:28:06 PM UTC, gregebert wrote:
>
> Try an inductor witrh the same inductance, and a higher Isat rating.
>

I had the same problem that Oyvind is describing and uprating the inductor 
fixed it nicely. I haven't had the time to go back and quantitatively 
analyse the circuit behaviour to understand exactly how I got it wrong in 
the first place - the original inductor choice should have been OK. But 
perhaps in practice you have to allow much more margin on Isat than I had 
assumed.

Jon.

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[neonixie-l] Re: Single inductor supplies and heat issues

[Oyvind]

The FET's (and diodes) I'm using, are well within the specs. None of those 
show any sign of heat at all. Also, I am using FET's with low QG/Rds etc.

My own supply uses a current-sense resistor, which I can be used for 
measuring purposes.

Most of the commonly used supplies runs around 40-60kHz, and uses 100uH 
inductors (DCM).

I am actually looking into using (much) higher inductance and higher 
frequencies. So far simulations looks OK, and I get "CCM-ish" curves and 
reasonably good efficiency. Will do some more simulations before I make a 
test board.

What particular things are you thinking about ?





On Tuesday, November 6, 2018 at 6:02:48 PM UTC+1, gregebert wrote:
>
> Also, be sure to use a scope and look carefully through the design. The 
> switching device (most likely a MOSFET) is susceptible to voltage 
> overstress, so make sure the drain-source voltage is not exceeded, and 
> especially not the gate-source voltage because it is a very thin oxide that 
> can only withstand low voltages, on the order of 10-20 volts.
>
> If you can place a small resistor, say 0.1 to 1.0 ohms, between the source 
> lead and GND, you can use a scope to monitor peak transistor current, which 
> in-turn will be the peak inductor current. It must remain below Isat.
>
> The transistor is subject to heating as well, depending upon its Rds (on) 
> spec and the RMS current thru the inductor. Switching losses are probably 
> small, but the only way to know is to measure the drain-source voltage 
> simultaneously with the drain current. Some fancy scopes might calculate 
> this for you, otherwise you can export data-samples to excel and calculate 
> the switching energy per-cycle.
>
> Knowing the RMS current thru the inductor, and it's resistance, you can 
> calculate the resistive power dissipation; this does NOT include any 
> magnetic losses due to hysteresis or saturation.
>
> If you are running at high frequencies, such as hundreds of kilohertz, 
> other things will creep-in and bite you.
>

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[neonixie-l] Re: Single inductor supplies and heat issues

[gregebert]

Also, be sure to use a scope and look carefully through the design. The 
switching device (most likely a MOSFET) is susceptible to voltage 
overstress, so make sure the drain-source voltage is not exceeded, and 
especially not the gate-source voltage because it is a very thin oxide that 
can only withstand low voltages, on the order of 10-20 volts.

If you can place a small resistor, say 0.1 to 1.0 ohms, between the source 
lead and GND, you can use a scope to monitor peak transistor current, which 
in-turn will be the peak inductor current. It must remain below Isat.

The transistor is subject to heating as well, depending upon its Rds (on) 
spec and the RMS current thru the inductor. Switching losses are probably 
small, but the only way to know is to measure the drain-source voltage 
simultaneously with the drain current. Some fancy scopes might calculate 
this for you, otherwise you can export data-samples to excel and calculate 
the switching energy per-cycle.

Knowing the RMS current thru the inductor, and it's resistance, you can 
calculate the resistive power dissipation; this does NOT include any 
magnetic losses due to hysteresis or saturation.

If you are running at high frequencies, such as hundreds of kilohertz, 
other things will creep-in and bite you.

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[neonixie-l] Re: Single inductor supplies and heat issues

[gregebert]

Most likely., the inductor is exceeding it saturation current. That is the 
point where additional current does not add much magnetic energy, and at 
that point you will see an increase in lost energy (heat).
Try an inductor witrh the same inductance, and a higher Isat rating.

My experience with any sort of switching converter is that they work great 
at low loads, and as you increase the load you see more problems.

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