On 03 Apr 2024 12:07:10 -0700, peter@easthope.ca wrote:

>A variable power adapter is required to drive a 6 V, 30 W incandescent
>bulb in a microscope.
>
>Similar to the 3-12 V 5 A adapter here.
>https://www.ebay.ca/itm/305207182573
>An adapter providing 1.5-6 V output would be better but I haven't
>found one.
>
>Rather than limit the adjustment to 6 V, I think of halving the
>output. An integrated circuit in a 4 port package is conceivable.
>https://www.youtube.com/watch?v=VJfqBQ2ybpk
>
>Does the marketplace offer a solution?
>Another idea?
>
>Thanks, ... P.
>
>
What does the microscope manufacturer supply for this function?

If you have a >6V source, simple 555-type buck regulators are
available with minimum output listed as 1.8V

https://www.aliexpress.com/item/1005006482720286.html?

These generally regulate the negative output terminal, unfiltered.
This would not be an issue for an isolated 6V incandescent lamp.

Rl

In article <vhct0j9ao9d75ad7dr47r4eha1t9knt5d2@4ax.com>, legg <legg@nospam.magma.ca> wrote:
> What does the microscope manufacturer supply for this function?

The scope is a Zeiss OPMI 1. Google finds many listings of various
models with various power supplies.

This scope was donated without the power supply; I can't say what the
original supply was but Zeiss built nice equipment capable of
continuous and reliable duty.

> If you have a >6V source, simple 555-type buck regulators are
> available with minimum output listed as 1.8V
>
> https://www.aliexpress.com/item/1005006482720286.html?
>
> These generally regulate the negative output terminal, unfiltered.
> This would not be an issue for an isolated 6V incandescent lamp.

Good idea. Will see what Lee's Electronics has in stock. I expect to
have to limit the voltage somehow to prevent burning the bulb.

Thanks, ... P.

On 04 Apr 2024 09:37:02 -0700, peter@easthope.ca wrote:

>In article <vhct0j9ao9d75ad7dr47r4eha1t9knt5d2@4ax.com>, legg <legg@nospam.magma.ca> wrote:
>> What does the microscope manufacturer supply for this function?
>
>The scope is a Zeiss OPMI 1. Google finds many listings of various
>models with various power supplies.
>
>This scope was donated without the power supply; I can't say what the
>original supply was but Zeiss built nice equipment capable of
>continuous and reliable duty.
>
>> If you have a >6V source, simple 555-type buck regulators are
>> available with minimum output listed as 1.8V
>>
>> https://www.aliexpress.com/item/1005006482720286.html?
>>
>> These generally regulate the negative output terminal, unfiltered.
>> This would not be an issue for an isolated 6V incandescent lamp.
>
>Good idea. Will see what Lee's Electronics has in stock. I expect to
>have to limit the voltage somehow to prevent burning the bulb.
>
>Thanks, ... P.

Using a lower voltage wall wart as a source is the easiest limiting
method. Overvolting the bulb by 50% temporarily will not be
catastrophic. If the wall wart is internally limited for power or
current, then overvoltage is unlikely.

There may be issues with wall wart curremt limiting which is best
addressed with filtering (~ capacitive) between the two devices.

The 555 buck regulators are dumb, in themselves, which is often an
advantage driving nonlinear (incandescent) loads. The unit with the
large yellow PTC on-board is a good bet as load protection.

Just remeber that the 'common' rail in the system will be the +rail
of the 555 buck output. The wall wart won't care - neither will
the lamp. You're effectively driving the lamp with a negative supply.

The unfiltered output is a high frequency square wave with peaks
equal to the wall wart's labelled voltage.

Filtering that output to DC would require an external 5A buck diode,
a 5A choke and an electrolytic cap - effectively doubling the size,
weight (and cost) of the regulator section, at no benefit to the lamp.

RL

On 04 Apr 2024 09:37:02 -0700, peter@easthope.ca wrote:

>In article <vhct0j9ao9d75ad7dr47r4eha1t9knt5d2@4ax.com>, legg <legg@nospam.magma.ca> wrote:
>> What does the microscope manufacturer supply for this function?
>
>The scope is a Zeiss OPMI 1. Google finds many listings of various
>models with various power supplies.
>

If you are intending use of this device in it's intended environment,
you should use the mfr's designated power supply, as this is the
major system component that gives it biomedical safety certification.

RL

I also note that in the zeiss opmi_1 manual, a 12V 100W halogen lamp
is specified - and a self-resetting thermal limiter is built into
the lamp holder.

RL

legg wrote:

> I also note that in the zeiss opmi_1 manual, a 12V 100W halogen lamp
> is specified - and a self-resetting thermal limiter is built into
> the lamp holder.
>
> RL

Temu has an enclosed 0-12v LED dimmer for $2.69 that might work with a
wall wart but only "rated" for 8A.

On Sat, 06 Apr 2024 21:14:03 GMT, "John Keiser" <johnkeiser@juno.com>
wrote:

>legg wrote:
>
>> I also note that in the zeiss opmi_1 manual, a 12V 100W halogen lamp
>> is specified - and a self-resetting thermal limiter is built into
>> the lamp holder.
>>
>> RL
>
>Temu has an enclosed 0-12v LED dimmer for $2.69 that might work with a
>wall wart but only "rated" for 8A.

The zeiss opmi_1 uses a light pipe.

RL

RL and all,

In article <3hot0jdfedfel1pm82vnqbn04u2bq29q37@4ax.com>, legg <legg@nospam.magma.ca> wrote:
> I also note that in the zeiss opmi_1 manual, a 12V 100W halogen lamp
> is specified - and a self-resetting thermal limiter is built into
> the lamp holder.

You have an original paper manual?

OPMI 1 is a family of microscopes rather than a specific model;
correct?

A search in eBay, for example, finds many variants. Appears that
components were assembled according to requirements of a customer.

A search found this URL.
http://www.frankshospitalworkshop.com/equipment/documents/microscopes/user_manuals/Zeiss%20OPMI%201%20FC%20Surgical%20Microscope%20User%20Manual.pdf

The 2nd supplementary page after page 31 lists these bulbs.

Endure Number Spare Bulbs

90-1200 Zeiss 6V 30W Bt58Z 390158
90-1201 Zeiss 6V 50W Bt86Z 390186
90-1202 Zeiss 12V 100W HLX #64626 380075 1020
90-1203 EFR Housing #900
90-1204 Zeiss 15V 150W EFR 310198
90-1205 Zeiss 12V 100W HLX #64627 380079 9040
90-1206 Zeiss Superlux 40
90-1207 Zeiss Superlux 175
90-1208 Zeiss Superlux 300 with Cartridge
90-1209 Zeiss Superlux 300 Bulb Only - No Housing or Meter

90-1302 ELS 150 21V 150W EKE
90-1400 ELS 250 24V 250W ELC
90-1403 ELS 24 60V 24W Metal Halide
90-1402 ILO 300W with Cartridge

EFR, ELS and ILO are bulb manufacturers?

After my original enquiry, also found a page for a replacement LED
illuminator. 700+ $US. Beyond my budget at present.

Also found some old bulbs in boxes labeled 390153. They have the
unusual (Zeiss?) triangular base and the filament is parallel to the
bulb axis. The 39015 has the filament crosswise to the bulb axis.

Also found an inexpensive motor controller which adjusts light
intensity nicely. The adjustable power brick can be set to deliver 6
V. The controller connected beyond that adjusts intensity.

In case a 90-1202 Zeiss 12V as listed above turns up, my power supply
should suffice for that also.

Thanks to all for the replies, ... P.

On 24 Apr 2024 15:35:43 -0700, peter@easthope.ca wrote:

>RL and all,
>
>In article <3hot0jdfedfel1pm82vnqbn04u2bq29q37@4ax.com>, legg <legg@nospam.magma.ca> wrote:
>> I also note that in the zeiss opmi_1 manual, a 12V 100W halogen lamp
>> is specified - and a self-resetting thermal limiter is built into
>> the lamp holder.
>
>You have an original paper manual?
>
>OPMI 1 is a family of microscopes rather than a specific model;
>correct?
>
>A search in eBay, for example, finds many variants. Appears that
>components were assembled according to requirements of a customer.
>
>A search found this URL.
>http://www.frankshospitalworkshop.com/equipment/documents/microscopes/user_manuals/Zeiss%20OPMI%201%20FC%20Surgical%20Microscope%20User%20Manual.pdf
>
>The 2nd supplementary page after page 31 lists these bulbs.
>
>Endure Number Spare Bulbs
>
>90-1200 Zeiss 6V 30W Bt58Z 390158
>90-1201 Zeiss 6V 50W Bt86Z 390186
>90-1202 Zeiss 12V 100W HLX #64626 380075 1020
>90-1203 EFR Housing #900
>90-1204 Zeiss 15V 150W EFR 310198
>90-1205 Zeiss 12V 100W HLX #64627 380079 9040
>90-1206 Zeiss Superlux 40
>90-1207 Zeiss Superlux 175
>90-1208 Zeiss Superlux 300 with Cartridge
>90-1209 Zeiss Superlux 300 Bulb Only - No Housing or Meter
>
>90-1302 ELS 150 21V 150W EKE
>90-1400 ELS 250 24V 250W ELC
>90-1403 ELS 24 60V 24W Metal Halide
>90-1402 ILO 300W with Cartridge
>
>EFR, ELS and ILO are bulb manufacturers?
>
>After my original enquiry, also found a page for a replacement LED
>illuminator. 700+ $US. Beyond my budget at present.
>
>Also found some old bulbs in boxes labeled 390153. They have the
>unusual (Zeiss?) triangular base and the filament is parallel to the
>bulb axis. The 39015 has the filament crosswise to the bulb axis.
>
>Also found an inexpensive motor controller which adjusts light
>intensity nicely. The adjustable power brick can be set to deliver 6
>V. The controller connected beyond that adjusts intensity.
>
>In case a 90-1202 Zeiss 12V as listed above turns up, my power supply
>should suffice for that also.
>
>Thanks to all for the replies, ... P.

In the reference I found for zeiss opmi_1, illumination is
delivered to the optics package through a long (1m ?) light
pipe (or possibly bundles of same).

RL