This sounds like an ideal application for a pulse-width modulated (PWM) power source, with negative feedback from a temperature sensor (thermistor, RTD, or thermocouple) to control the final cooler temperature. Hang your bridge rectifier and filter capacitor on the transformer and build on from there. Pay attention to
@Colin Mitchell advice on voltage regulation (or the lack thereof) when choosing components.
There are lots of PWM circuits on the Internet, and most do not require voltage regulation to produce a constant-current drive for your Peltier device. If I were building this, I would assemble an Arduino Uno along with a power MOSFET, a thermistor, and a few resistors and diodes to create a proportional power controller in software. You can add integral and derivative feedback too, but that is generally not necessary for static applications where the external variables don't change rapidly. A simple correction for "droop," which is the difference between set-point and actual temperature that is a characteristic of a proportional-only controller, can be provided with a potentiometer to allow adjustment of the final temperature, as visually read out on a simple numeric display. IIRC. PWM offers automatic integral action when implemented in software. Total cost I estimate to be less than fifty bucks American, maybe less if you have a well-stocked "junke box" of parts you can re-cycle from other projects.
As for simulation... Linear Technology has a free pSPICE program (
LTspice IV) with schematic-capture that you can download. Draw the schematic and run the simulation from it. Play "what if" scenarios with the component values. Tons of fun! This will help you design the PWM constant-current Peltier driver, which is an analog circuit. They also have an extensive library of application notes, oriented toward their products of course, but of general usefulness no matter whose products you use. But remember simulation is not reality. You have to actually build something with real parts and "let the smoke out" once in a while to learn anything.
Ummm... what is your experience and desire for the sort of thing I have outlined above? Off-the-shelf solutions are possible of course, but that's not generally what we are here for.
